


^^_j||||i||y^ 



THE 



MARmE STEAM-ENGINE. 



THOMAS J. MAIN, M.A. F.R.Ast.S. 

MATHEMATICAL PROFESSOR AT THE ROYAL NAVAL COLLEOE, PORTSMOUTH 
AND 

THOMAS BROWN. Assoc. Inst. C.E. 

CHIEF ENttlNEER, R.N., ATTACHED TO THE R.N. COLLEGE. 



FROM THE FOURTH LONDON EDITION. 



PHILADELPHIA: 
HENRY CAREY BAIRD, 

INDUSTETAL PUBLISITER, 

40 6 WALNUT STREET. 

1S65. 






iv Tran8r»r 
AUG 12 1927 



k 



PREFACE. 



The various publications that have appeared of late years on the 
Steam-engine render necessary an explanation of the reason for 
adding one to the Hst : the authors of the present work feel that 
they might otherwise he open to the charge of presumption, con- 
sidering the eminent talents which have been employed on the 
subject. The works hitherto published have, while abounding in 
excellences, been wanting more or less in the kind of information 
eagerly sought after by those intrusted with the charge of steam- 
vessels, and which is rarely acquired ^cept through the medium 
of oral mstruction. Some of them, containing little more than 
a description of the parts of an engine, and of their uses, are 
simply elementary treatises. Some are chiefly valuable to manu- 
facturers, from their containing elaborate details about the dimen- 
sions and strength of rods, bars, beams, etc. Some are mainly 
occupied with criticisms and comparisons of the various kinds of 
engines or propellers in use at the present day. All are valuable 
to the several classes of readers to which they are addressed; 
they contain in the aggregate nearly all that can be said on the 
history and purposes of the Steam-engine : but individually they 
fail to impart that precise and readily available knowledge which 
ought to be possessed by every naval officer and by every engineer 

Having e:xperienced, while in the course of instructing others, 
during many years, the want of a practical work for reference, the 
authors have been in the habit of supplying the deficiency by 
manuscripts drawn up for the purpose ; and having derived manifest 
advantage from their use, being moreover encouraged by the 
advice of their friends, they have been induced to publish them in 
a carefully arranged form with the object of facilitating thereby the 
labors of officers studying at the Eoyal Naval College, and with 
the hope of being, in some measure, of service to all who may 
be interested in acquiring steam-knowledge as applied to nautical 
purposes. 

Existing works on steam are generally deficient in maxims for 
the management of engines in the various circumstances of difficulty 



jv PEEFACE. 

and doubt in which steam-vessels, whether of the Navy or the 
merchant-service, may be placed. These, however, are the ends for 
which practical men read such works. When at sea they are neces- 
sarily thrown on their own resources in every emergency, and 
therefore a sound rule, framed by experience and previous reflec- 
tion, is of more value than a scientific investigation. It can matter 
l^ut little, practically speaking, to the captain or engineers of a 
steamer, whether side-lever or direct-acting, oscillating or trunk 
engines are preferable, or whether ^the paddle or screw have the 
advantage as an instrument of propulsion : but it does matter very 
seriously to them, that they should be capable of tracing the imper- 
fect working of an engine to its right cause, and be able to remedy 
any defect ; that they should be skilled in the modes of economizing 
fuel, on which the efficiency of a steam-vessel mainly depends ; and 
that they should, by a due knowledge of the skilful management of 
engines, and of the relation of their parts to each other, be able 
to diminish the inconvenience of a gale of wind, and be prepared 
against accidents. Impressed with this view, the authors have 
endeavored to give a practical tendency to their work throughout, 
without, however, neglecting the considerations which are due 
to science. While the reader who has not had the advantage 
of a mathematical education will be able to peruse the work as 
far as the Miscellaneous Chapter without meeting with an obstacle 
to its full comprehension, the scientific reader will find in notes, and 
at the end of the work, the investigations of the rules. 

While the authors hope that the work now offered to the public is 
a step in the right direction, they are conscious of its many deficien- 
cies, arising from its having been compiled in the midst of other 
business which did not admit of delay. Many of the rules also must 
be considered as empirical, especially those relating to an action, 
and are the result of reflection rather than of experience. 



NOTE TO THE AMERICAN EDITION. 



The authors having made such extensive revisions and improve- 
ments in the present, or fourth edition of "The Marine Engine," 
it is deemed important to give the following information for the 
guidance of those who have purchased their "Questions on Sub- 
jects connected with the Marine Steam-Engine." In the last named 
volume constant references are made" to articles and pages of the 
present volume. Those references however are to the third edition. 
The accompanying table gives in one column the numbers of these 
articles and pages in the third edition, and in another column those in 
the fourth or present edition. By reference to this table the number 
of any such article or page as now printed can be had at a glance. 

TABLE OF AETICLES AND PAGES. 





Third 


Fourth 




Third 


Fourth 




Third 


Fourth 




Edition. 


Edition. 




Edition. 


Edition. 




Edition. 


Edition. 


Art. 


30 


36 


Art. 


129 


145 


Art. 


244 


223 




31 


37 




134 


151 




250 


229 




72 


98 




135 


152 




251 


230 




74 


99 




136 


153 




253 


232 




75 


out 




141 


156 




2.54 


234 




76 






142 


157 




257 


237 




77 


u 




145 


160 




259 


239 




78 


100 




153 


165 




264 


244 




79 


101 




157 


167 




265 


245 




80 


102 




158 


168 


" 


268 


249 




81 


103 




161 


171 




278 


259 




87 


out 




170 


182 


u 


284 


265 




89 


106 




173 


185 




303 


283 




90 


107 




177 


189 




304 


284 




91 


108 




180 


190 




307 


287 




92 


109 




182 


64 




308 


288 




96 


113 




183 


65 




309 


289 ! 




97 


114 




184 


66 




317 


297 : 




98 


115 




189 


74 




331 


310 




101 


out 




190 


75 


a 


338 


316 




102 


117 




191 


76 




339 


317 




106 


121 




198 


81 




341 


319 


,, 


108 


125 




206 


88 




342 


320 




109 


126 




207 


88 




343 


321 




110 


127 




209 


89 




347 


325 




111 


128 




217 


196 




362 


340 




113 


130 




220 


199 




364 


342 




114 


131 




224 


203 






1 




115 


132 




228 


207 


page 


298 


282 1 




119 


136 




230 


209 




300 


284 




121 


138 




231 


210 


'< 


304 


287 




124 


140 




237 


216 


<< 


307 


290 • 


a' 


126 


■ 142 




240 


219 


u 


309 


292 



PLATE I. 



REFEEENCES. 



A' A^ Interior of Cylinder. 
B B Cylinder-jacket. 
C Expansion-valve. 
D Interior of Slide-casing. 
E E E Slide-casing. 

F F Upper andLower Steam- 
ports. 
G G Gr Condenser. 
HHHH Piston. 

1 1 Piston-rod. 
K Foot-valve. 
L L Air-pump. 
M M Air-pump Bucket. 
N N Butterfly-valves. 
Hot Well. 
P Air-cone. 
Q Delivery-valve 
E E Stuffing-box of Cylin- 
der. 
S S Stuffing-box Cover. 
T T Metallic-Eing (or Pack- 
ing). 
Z Lower Escape-valve. 
a Steam-pipe opening in- 
to the Jacket. 
d Slide-rod. 



PLATE IL 



REFERENCES. 



B B Cylinder. 
E E E Slide-casing. 

1 Piston-rod. 
E E Stuffing-box. 

S S S Stuffing-box Gland 
Cover). 
U U Cylinder Cross-head. 
X X Cylinder Side-rods. 

Z Lower Escape-valve. 
Z' Z" Side-levers. 
, 1 1 Weigh-shaft, or Bar. 

2 Gab-lever. 

3 3 Yalve-Hfter. 

4 4 Back-balance. 

5 5 D-Slide Cross-head. 
6 D-Slide-rod. 

g g Fork-head. 

p Main Centre. 
q q Paddle-shafts, 
r r Cranks. 
s Connecting-rod. 

1 1 Connecting-rod Brasses. 
V V Air-pump Cross-head. 
y y Air-pump Side-rods. 



VI 



(or 



CONTENTS. 



INTRODUCTORY CHAPTER. 

ART. PAGE 

1. Steam, definition of 15 

2. Water, definition of. 15 

3. Caloric, definition of. 15 

4. Temperature, definition of 16 

5. Heat and cold, definition of 16 

6. General efi'ects of heat and cold 16 

7. Expansion by heat 16 

8. ^ of gases .' 16 

9. Practical methods of observing expansion 17 

10. Various applications of this principle 17 

11. Law of expansion by heat not universal 19 

12. Beneficial result arising from this anomaly .■ 19 

13. To show that the law fails in the foregoing case 20 

14. To ascertain th-e temperature of any substance. 20 

15. Pyrometer, description of 20 

16. Thermometer, description of 21 

^ I — method of graduating .• 22 



1 



to compare when differently graduated 22 

18. Cooling, laws of. 23 

19.. Conduction 24 

20. Conducting powers of bodies 25 

21. The sensations a bad criterion of temperature 26 

22. Convection 26 

23. Advantages to be derived from as knowledge of this law 27 

24. Explanation of some natural phenomena 28 

25. Radiation 29 

26. Radiating powers of bodies — what it depends on 29 

27. Land and sea breezes 30 

28. Capacity for heat 31 

29. Caloric, unit of 31 

30. Latent heat 32 

31. Under what circumstances heat becomes latent 32 

32. Heat the sole agent in melting and vaporizing bodies 33 

5 



6 CONTENTS. 

ART. PAQE 

33. Calorimeter 34 

34. Sources of heat 35 

35. Heat generated by mechanical operations 35 

36. Combustion 35 

37. temperature necessary .for 36 

38. Oxidation 37 

39. Effects of galvanic action 38 

40. Boiling-point. 39 

41. as influenced by pressure 39 

42. Temperature of steam : 40 

43. Yapor 40 

44. Formation of dew 41 

45. Causes influencing the formation of dew 41 

46. Yapor and steam distinguished 42 

47. Steam, method of obtaining 42 

48. Steam distinguished from other elastic fluids 43 

49. Boiling-point of fresh water 43 

50. salt water 44 

51. The steam of salt water is fresh 44 

52. Distillation, process of. 44 

53. High-pressure steam 45 

54. Measure of steam by atmospheres 45 

55. Laws regulating the pressure of steam 45 

56. Pressure, density, and temperature of steam. 45 

57. "' " " " " 46 

58. Specific gravity of steam 47 

59. Common ste-am 48 

60. Superheated steam 48 

61. Sea-water, analysis of. 49 

62. saline contents of. 50 

63. gaseous matter in 50 

CHAPTER n. 

THE BOILER, 

64. Marine boilers distinguished from land boilers 51 

65. Gear connected with boilers 51 

66. The tubular boiler 53 

67. The number of boilers in each steam vessel 55 

68. The steam-chest 56 

69. The fire-bridge 56 

70. Ash-pits 57 

71. Gunboat boilers 57 



CONTEN^TS. 7 

ART. PAa3 

72. Exhaust-pipe j 58 

73. Blast-pipe 58 

74. Feed or donkey engine 59 

75. Boiler hand-pumps 59 

76. The safety-valve .*. 61 

77. Gear attached to the safety-valve 62 

78. Under what circumstances the weights of the safety-valves 

may be increased 63 

- 79. The safety-valve box.. 63 

80. Waste-steam funnel and drip-pipe 64 

81. Steam-gauge ; 65 

82. for high-pressure boilers 66 

83. Gauge-cocks. 67 

84. Boiler water-gauge 67 

85. Kingston's valves 68 

86. Wash^plates or dash-plates 68 

87. Dampers 69 

88. The reverse-valve 69 

89. Communication or stop-valve 71 

90. Blow-out cocks 72 

91. Brine-pumps, brine-valves, and refrigerators 73 

92. Surface blow-out pipes 74 

93. Seward's brine-valve 75 

94. Brine and feed valves, as fitted at the factory, Portsmouth 

Dockyard 75 

CHAPTER III. 

THE ENGINE. 

95. Steam-engine, definition of. 77 

96. Employment of the several methods 77 

97. Engine in general use previous to Watt's improvement.. . 78 

98. Newcomen's engine 78 

99. Discoveries of Watt 81 

100. Single-acting engine 82 

101. '' '' " 83 

-. * [ Double-acting engine 85 

104. High-pressure or non-condensing engine. 86 

105. Marine Steam-engine 86 

106. Side-lever marine engine 86 

107. Blow-valve 90 

108. Stuffing-boxes, etc 90 



8 CONTEXTS. 

AKT. PAGE 

109. Piston of steam-cylinder 91 

110. Working parts of side-lever engines 92 

111. Slide, method of working 94 

112. Strap, gib, and cutter 95 

113. Escape-valves of cylindef 96 

114. Parallel motion 97 

115. Surface condensation 99 

116. Test-cocks 100 

117. Foot-valve not absolutely necessary 101 

118. Annular air-pimip bucket 101 

119. Annular delivery-valve ^ 102 

120. Air-pump and common pump contrasted 102 

121. Delivery-valve not always needed. 102 

122. Double-acting air-pump 103 

123. Discharge or sluice valve 103 

124. Yarious kinds of slides 103 

125. Long D-slide 103 

126. Short D-slide .104 

127. Locomotive slide 105 

128. Seward's slides..' 106 

129. Cylindrical slides 107 

130. Cushioning 107 

131. Lead of slide 108 

132. Lap of slide 109 

133. Effect of lap 110 

134. " " Ill 

135. Working with and without lap contrasted Ill 

136. The eccentric 112 

137. Throw of eccentric 114 

138. Stops on the eccentric 114 

139. To find the travel of the slide 116 

140. Double eccentric - 116 

141. Throttle-valve 117 

142. Expansion-valve 118 

143. Expansion valves 120 

144. Hornblower's valve i 120 

145. Cornish double-beat 121 

146. Equilibrium-valve 122 

147. Yalves of H. M. S. Penelope 123 

148. Grid-iron Yalve 124 

149. Other kinds of expansion-valves 125 

150. Maudslay and Field's rotary expansion-valves 125 

151. Condenser-gauge 127 



CONTENTS. 9 

AST. PAGE 

162. Pressure in condenser by gauge 129 

153. Errors in Barometer-gauge 130 

154 Mode of correcting ditto 131 

155. Lubricators 131 

156. Expansion-cams and gear.. 132 

157. Feed-pumps * 134 

158. Bilge-pumps 136 

159. Modes of propulsion 137 

160. Paddle-wheels -. 137 

161. Feathering-paddles 138 

162. Eeefingthe paddles,... *. 138- 

163. Disconnecting the wheels 139 

164. Methods of disconnecting paddle-wheels 139 

165. Immersion of paddle-wheels 140 

166. Paddle-wheel brakes 140 

167. The Screw-propeller 141 

168., Definition — length of screw 142 

169. angle of screw.. 142 

170. Pitch of screw 142 

171. Slip of screw 142 

172. Area of screw 143 

173. Thread of screw.... 143 

174. Diameter of screw 143 

175. Disconnecting the screw 144 

176. Methods of raising the screw 144 

177. Governors in screw-ships 145 

CHAPTER lY. 

178. Direct-action engines 146 

179. Gorgon engines 147 

180. Length of radius-bar of ditto 149 

181. Fairbairn's engines 151 

182. Maudslay's double-cylinder engines 152 

183. Boulton and Watt's direct engines 154 

184. Messrs. Miller and Ravenhill's direct engines 155 

185. Oscillating engines '. 155 

186. Engines for working the screw-propeller 156 

187. Direct-acting screw-engines 157 

188. Direct-acting geared engines 158 

189! Oscillating horizontal engines 159 

190. Trunk engines 159 

191. Double-acting air-pump 161 



10 CONTENTS. 

ART. PAGE 

192. Maudslay and Field's return connecting-rod engine 161 

193. Humphrey's engine 162 

CHAPTER Y. 

GETTING UP THE STEAM. 

194. Filling the boilers 163 

195. To know when the blow-out cocks are closed 164 

196. On the proper height of water in the boilers when fires are 

first lighted 164 

197. Laying the fires 164 

198. To get up the steam expeditiously 165 

199. Duties to engine, etc., while the steam is getting up 165 

200. Injection-orifice choked up 168 

201. To see the engine clear for starting 170 

202. Foot-valve gagged. 170 

203. " '' " 171 

204. Starting the engines 172 

205. Starting with one engine in gear 173 

206. Working engines at moorings 173 

207. On starting from moorings before the steam is well up 174 

208. Steaming through an intricate passage on first starting. . . 175 

209. On opening the communication between a hot and cold 

boiler 176 

210. Priming on first starting the engines 176 

211. On priming while getting up the steam 177 

212. Remedies against priming 177 

213. Chilling eff"ects of cold surfaces 178 

214. Banking-up the fires 178 

215. Putting back the fires 179 

216. Safety-valves to be closed when banking-up 180 

217. On the steam-gauges of strange boilers 180 

218. Attention to the jackets of steam-cylinders 181 

219. To ascertain if blow-out cocks are opened 181 

CHAPTER YI. 

DUTIES TO MACHINERY WHEN UNDER STEAM. 

220. The boiler 183 

221. Class water-gauge 183 

222. Blowing out 184 

223. On the limit of saturation 186 

224. The salinometer 190 

225. Ash-pits to be kept clear of ashes 190 



CONTENTS. 11 

AKT. PAGE 

226. On stoking 191 

227. Fires, management of 192 

228. Feeding the boilers 193 

229. To prevent saturation of boilers under peculiar circum- 

stances • 193 

230. Decrease in maximum boiler-pressure when the ship is 

rolling 194 

231. Blowing-out to be Hmited at times 194 

232. On the number of boilers to be employed 195 

233. Superheating apparatus 197 

234. Ashes escaping from the funnel 198 

235. Flame appearing at the top of the funnel 199 

236. On the supply of air to the fires 200 

237. To prevent accidents if the water be low in the boilers. . . . 200 

238. Effect on the steam from admitting a large supply of 

cold water 201 

239. Attention to be paid to injection-pipes 201 

240. Kingston's valves 204 

241. Working as high-pressure engines 205 

242. Injecting from the bilge 205 

243. On leaks in the engines 206 

244. Method of working engines with leaky slides 208 

245. Leaky condensers or air-pumps 208 

246. Feed-pumps, attention to be paid to 210 

247. Dampers and ash-pit doors, attention to be paid to 210 

248. Back-lash 210 

249. Bearings of engines, duties to •. 211 

250. Soft metal for bearings * 213 

251. Expansive working 213 

252. Steam-circle 214 

253. Management of fuel 215 

254. Previous notice to be given before stopping the engines. . . 216 



CHAPTER YII. 

DUTIES TO MACHINERY DURING AN ACTION, OR AFTER AN 
ACCIDENT. 

255. Gear for repairing damages during an action 218 

256. Machinery to be examined before an action 218 

257. Precautions against fire 219 

258. Regulation of fires during an action 219 

259. Casualties to paddle-wheels during an action 221 

260. Efi'ect of shot upon funnels 222 



12 CONTENTS. 

ART. PAGE 

261. Bemedies proposed if shot qnter .the boiler 224 

262. Regulation of the steam during an action 225 

263. Temporary repairs to a boiler 225 

264. of a steam-pipe or feed-pipe 226 

265. Method of working one engine 227 

266. Screw-propeller, remarks on 228 

267. To clear the bilge of a vessel.. 229 

268. Precautions in case a vessel be run ashore. 229 

269. Temporary repair of boiler-tubes 230 

270. Steamer in chase 230 

271. Funnel, to repair after an action 231 

272. To straighten a bent piston-rod 231 

273. To work engines without cylinder-covers 232 

CHAPTER VIII. 

DUTIES TO ENGINE, ETC, ON AEEIVING IN HARBOE. 

274. Blowing out the water 234 

275. Hauling out fires 234 

276. Engines, duties to, on arriving in port 235 

277. Lubricators to be examined .». . 236 

278. Bearings to be examined 236 

279. Remarks on the outer bearings of paddle-shafts 237 

280. on piston-glands, keys, etc 237 

281. On screwing down the " holding-down bolts". 237 

282. On examining, repacking, etc., slides 238 

283. To find the length of stroke of an engine 241 

284. To adjust the parallel motion of engines 241 

285. " " " '' " " " , 244 

286. Paddle-shafts, to adjust 245 

287. SUdes, to set. 248 

288. " '' '' 252 

289. Eccentric-rod, to adjust 253 

290. Remarks on alteration of the sUdes 253 

291. On cleaning out and scaling the boiler 255 

292. Rust-joints 257 

293. On stopping cracks in boilers, etc 257 

294. On repairing the fire-bridges and ash-pits 258 

295. On staying the boilers 258 

296. On increasing the load in the safety-valve 259 

297. Boiler water-glass 259 

298. On the internal feed-pipe 260 

299. The steam-gauge to be examined occasionally 260 

300. On replacing the fire-bars 260 



CONTENDS. 13 

ART. PAGB 

301. On sweeping the funnel 261 

302. Coal-bunkers to be examined.*. 262 

303. Coaling ship 263 

304. Rubbish to be carefully removed after repairs 263 

305. Danger from impure air in boilers , 264 

306 Screw-gearing in screw-steamers 264 

307. Lubricating the gearing of screw-vessels 265 

308. Paddles • 265 

309. Preserving boilers when not in use 265 

310. On fitting mud-hole doors 266 

311. On getting up steam at frequent intervals 267 

312. On turning round the wheels by hand 268 

313. On turning the engines of screw-vessels.. . . .^ 268 

314. Raising cylinder-covers by tackles 268 

315. To get a cylinder-cover into its place 269 

316. To ascertain if the piston be steam-tight 270 

317. Piston loose on the rod .' 270 

318. Method of separating parts of an engine when rusted to- 

gether 271 

319. To blow-through when a blow-valve is not fitted 271 

320. Process of blowing-through, etc., delayed by cold 271 

321. Attention to engines of screw-vessels 272 



CHAPTER IX. 

MISCELLANEOUS. 

322. Efficiency of engines, measure of. 275 

323. Duty of an engine 276 

324. Horse-power of an engine 277 

325. Nominal horse-power .' 277 

326. Horse-power from the evaporation, etc 278 

827. On the screws of steam-vessels 298 

328. Approximate area of a screw-blade 299 

329. To find the angle of a screw-blade 300 

330. To find the pitch of a screw-blade 301 

331. Requisite pitch for a given speed of a screw 301 

332. To find the pitch from the speed of sliip and the sUp 302 

333. Area of a screw-blade (accurately).... , 302 

334. Power exerted by a screw 303 

335. Slip of the screw 306 

336. Best speed in a tide-way 307 

337. Motion of paddle-steamers in still water 308 

338. Consumption of fuel in a given time .... * 309 



14 CONTENTS. 

ART. PAGE 

339. On the consumption of fuel between the two ports 311 

340. On reefing paddles I 311 

341. Measure of performance of engines 312 

342. On the motion of the crank 313 

343. Work developed by a crank in one revolution 313 

344. Length of radius-bar 315 

345. Amount of work in one stroke of air-pump 316 

346. Amount of fuel lost by blowing-out 317 

347. Best temperature of a condenser 318 

348. On the qualities of fuel 321 

349. Weight of coal when used as fuel 322 

350. Patent fuel 322 

351. Effect on stowage on coals 324 

352. Decay of coals , 325 

353. Qualities of coals suited to navigation 325 

Table 1. Power and duty, etc., of various coals 327 

" II. Mean composition of average samples of various 

coals 329 

*' III. Average value of coals from different locahties. 332 
" TV. Average composition of coals from different 

localities 332 



APPENDIX. 

ART. PAGE 

354. To find the circumference of a circle 333 

355. area of a circle 333 

356. surface of a cylinder 333 

357. volume of a cylinder , 333 

358. surface of a sphere 333 

359. volume of a sphere 333 

360. volue of a cone 334 

361. Circular inch and square inch 334 

361. To find the area of an ellipse -. 3.34 

363. circumference of an ellipse 334 

364. Frustum of a cone, definition of. 334 

365. To find the volume of a frustum 334 

366. weight of any substance 334 

367. Useful rules to be observed when coaling 335 

Table A. Pressures of steam, and the corresponding temperatures and relative volumes 336 

" B. General effects of heat according to certain temperatures 3-37 

Table C. Of the linear expansion of solid bodies by heat 338 

Expansion of fiuids by heat 338 

D 339 

E 339 

F. Of capacities of bodies for heat referred to water as the standard 341 

G. Mechanical properties of materials 341 

H. Circumferences and areas of chcles of given diameters 345 

I. To find the pitch of a screw from the angle and diameter 354 

K. Knot-table 356 

Screw-steamers in her Majesty's Navy 3.57 

Paddle-steamers in her Majesty's Navy 361 

List of steam Gun-boats in the Royal Navy 363 

ALPnABETICAL INDEX SC6 



MARINE STEAM-ENGINE. 



INTKODUCTOKY CHAPTER. 

1. Steam. 

Steam is an elastic fluid generated from water by the 
application of heat. 

2. Water. 

Water is not a simple substance, but bas been discov- 
ered to be the result of the chemical union of two gases 
— oxygen and hydrogen. The experimental chemist 
proves this in various ways ; his most usual method being 
to take water and separate it into its two components by 
means of the galvanic battery ; or, to take the two gases, 
mixed together in their proper proportions, and by send- 
ing an electric spark through the mixture, he then finds 
the vessel which formerly contained the gases to be filled 
with steam, which condenses into water on the inside of 
the vessel. The gases are in their proper proportions 
when the volume of hydrogen is double that of oxygen. 

3. Caloric. 

Heat is only known to us by it& effects. Theories have 
been proposed to account for the various phenomena ; but 
as we are concerned only with the effects, it is not our ob- 
ject to enter into them in the present treatise. It will be 
2 * . 15 



16 EFFECTS OF HEAT. 

sufficient for us to state, that the cause of heat, whatever 
it may be, is called Caloric. 

4. Temperature. 
Temperature is a measure of the intensity of heat in any 
substance. 

5. Seat and Cold. 
The terms Heat and Cold represent, as is well known, 
opposite states of any substance as far as regards tempera- 
ture. It is universally admitted that cold merely expresses 
the absence of heat. 

6. General Effects of Seat. 
Heat acting on any material substance produces one or 
more of the following effects, viz. : 

Expansion. 

Liquefaction (of solids). 

Yaporization.(of liquids). 
And, on the contrary, if heat be abstracted from a sub- 
stance, it is attended with one or more of the following 
phenomena : 

Contraction. 

Solidification (of liquids). 

Liquefaction (of gases.) 

7. Expansion. 

As we have just stated, if heat be applied to a body, it 
is found, as a general law, that it will expand, and that it 
will contract in cooling ; but the rate at which a body or 
substance expands or contracts depends on its nature; 
gases universally expand more than fluids, and fluids more 
than solids. 

8. Expansion of Gases. 

All gases expand at the same rate ; thus if the amount 
by which a given volume of hydrogen gas expands for a 
given increase of temperature be ascertained, this will also 



EXPANSIONS-. 17 

give us the amount by wliicTi the same volume of dry 
steam expands for the same increase of temperature. An- 
other fact has been ascertained, viz., that the gases expand 
at the same rate at high and at low temperatures. But 
this is not the case with liquids or solids ; for each solid 
or liquid has its own rate of expansion, and they all ex- 
pand more sensibly at a high than at a low temperature 
(see Table of Dilatations, (C) in the Appendix). 

9. Practical Methods of observing the Expansion of Bodies. 

Let a bar of iron, which exactly fits a metal guage when 
cold, be heated ; and while in that state, let an attempt be 
made to introduce it again ; it will now be found to be too 
large, from having expanded. 

To make the expansion of liquids visible, let a glass 
bulb connected with a fine upright tube be filled with the 
fluid to be experimented on, and heated ; then as the fluid 
in the bulb becomes hot it will expand, and be partly 
forced up the tube, along which its motion will become 
sensible, from the fineness of the bore compared with the 
bulb. 

The effect of heat in expanding gases may be observed 
by partially filling a bladder with air, and then, after hav- 
ing closed it, immersing it in hot water for some minutes. 
The heat, penetrating the bladder, and acting on the gas, 
will cause it to make the bladder appear full. 

The difference in the rates of expansion of two metals 
may be shown by uniting together two thin strips of dif- 
ferent metals, such as copper and steel ; then, on the appli- 
cation of heat, since copper expands more than steel, it will 
be found that the strip will have assumed a curved form, 
having the copper on the outside and the steel on the 
inside. 

10. Applications of this Principle. 

It may become applicable in all those cases where 
metallic substances are required to secure materials to- 



18 ^ EXPANSION. 

getter ; if they be put on hot, they will contract by cool- 
ing, and form a closer union than conld be easily effected 
by manual labor. To this end the wheelwright and mast- 
maker put on their tires and hoops red-hot ; the cranks of 
the shaft of a steam-engine are put on the shaft while hot, 
and allowed to contract. Boiler-plates are riveted with 
red-hot rivets, which, by contracting in length on cooling, 
bring the two plates of iron closely together. 

The unequal expansion of different metals becomes a 
very useful property at times. As an instance, we may 
mention the nuts and screws of steam-engines. If they 
be made entirely of iron, the joint will be equally loose, 
whether the engine is hot or cold ; but if the screw be 
made of iron, and the nut of brass, the distance between 
the nut and the head of the screw will be less at a high 
than at a low temperature. This is particularly observable 
if the piston be secured to the rod by a brass nut. The 
difference in the rate of expansion of different metals is 
likewise applied to the compensation-pendulums of clocks 
and balance-wheels of chronometers, rods for measuring 
the base-line in trigonometrical surveys, etc. In many 
cases, also, accidents would occur if attention were not 
paid to the expansion of metals : thus in laying pipes for 
conveying steam or hot water, care is necessary that they 
do not abut against the walls of the building. Again, 
pipes for conveying gas or water underground are fitted 
with expansion joints, that the extremities of the pipes 
may have a little play throughoiit the length. The same 
must also be provided for in large iron constructions, such 
as iron bridges, sheds, etc. South wark Bridge is said to 
rise an inch at the crown in summer ; and it has been as- 
serted, that the heat of the sun during a summer's day 
produces more effect in deflecting the tubular bridge over 
the Menai Straits than the heaviest train would accomplish. 
If the iron dampers of chimneys be made flat, and become 
very hot, they will crack ; but if they be curved this will 



EXPANSION. 19 

not take place. If liot water be suddenly poured into a 
thick glass vessel it is apt to split, because the inner part 
expands before the outer surface is afiected. We shall 
hereafter see how this applies to the fire-bars of steam- 
boilers.* 

11. The Law of Expansion ly Heat not universally true. 
The law of expansion by heat is true, with the follow- 
ing exception : namely, that as hot water cools down from 
the boiling-point, it contracts till at 40^ Fahrenheit ; but 
if it be cooled helow this point, it begins to expand again ; 
and if it be kept perfectly still, it may be cooled even as 
much as 20° hehw the freezing-point in a liquid state, and 
the expansion will still proceed. It has also been supposed 
that clay contracts by heat ; but some are of opinion that 
the contraction of the whole mass arises from the particles 
coming into closer contact and lessening the air-spaces: 
moreover it does not again expand when heated a second 
time. 

12. A henefidal Result arising from the foregoing Anomaly. 
Since 40° is the temperature of maximum density for 
water, this, is approximately the temperature at very great 
depths, whatever be the climate at the surface, because if it 
were hotter or colder than this it would rise. Therefore, 
since the ice and the coldest water are lying on the surface 
in winter-time, they are quickly acted on by the returning 
heat of the sun, and the equilibrium of temperature is re- 
stored; on the other hand, if the general law were not 
violated, there would be an accumulation of ice every j^ear 
at the bottom of rivers, etc., which would be unaffected by 
the sammer sun ; and after a long interval, it is easy to 
imagine that the most disastrous consequences would 



^ Sudden contraction will also produce the same effect as sudden 
expansion. Thus glass plates and dishes are at times broken by 
putting ices in them. 



20 THE PYROMETER. 

ensue. See Whewell's Bridgewater Treatise. This anom- 
aly, however, is only discoverable in fresh water: for, 
according to Marcet, sea-water gradually increases in den- 
sity with the diminution of temperature. 

13. To prove that the general Law of Expansion fails in the 
foregoing Instance. 
Let two thermometers be made, one containing water 
and the other containing mercury; they will show the 
same temperature till they descend to 40° ; but if the 
room in which they are kept cools below 40°, the mercury 
thermometer Avill still show the true state of the room ; 
but the one filled with water will seem, by its expanding, 
to exhibit a higher temperature, thereby proving that the 
water has increased in bulk. Hence it is clear, apart from 
all other considerations, that water could not be used in- 
stead of mercury for a thermometer. 

14. To ascertain the Temperature of any Substance. 
The temperature of very hot bodies is found by an in- 
strument called the Pyrometer, and that of others whose 
temperature is above the freezing-point of mercury by the 
mercurial thermometer; while the temperature of very 
cold substances is ascertained by the alcohol thermometer. 
The latter instrument is a thermometer filled with alcohol 
instead of mercury, because alcohol is a substance that has 
never been solidified by cold. 

15. The Pyrometer. 
The most perfect pyrometer is that invented by Daniell. . 
Its action depends on the difference of expansion by heat 
between a platinum bar and a tube of well-baked black- 
lead ware, neither of these being liable to become fused by 
great heat. The metallic bar is shorter than the tube; 
and a short plug of earthenware is placed in the mouth of 
the tube above the platinum bar. It is secured in its 
place by a small wedge, so that it moves with difficulty 



THE THERMOMETER. 21 

when heated, and remains in its new position after the 
cooling (and consequent contraction) of the metallic bar. 
The expansion of the platinum bar thus obtained is meas- 
ured by adapting to the instrument an index^ which tra- 
verses a circular arc. The degrees marked on this scale 
are compared with those of the mercurial scale, and the 
ratio of the two marked, so that its degrees are converti- 
ble into those of Fahrenheit. 

16. The Mercurial Thermometer, 
This thermometer consists of a fine glass tube, having 
a bulb at one extremity filled with mercury, taking care 
that the tube be of perfectly uniform bore throughout the 
space traversed by the metal : the bulb is very thin, that 
the setisitiveness of the instrument may be the greater. It 
is filled with mercury in the following manner : The end 
of the tube opposite the bulb being open, the bulb is held 
over the flame of a spirit-lamp until the air inside is heated 
and rarefied ; the open end is then inverted, and immersed 
in a cup of mercury that has been previously boiled to de- 
prive it of its air-bubbles. As the air contained in the in- 
strument cools down, it contracts, and the pressure of the 
atmosphere on the surface of the cup forces the mercury up 
the tube, and partly fills the bulb. Let now the instrument 
be placed upright, with the bulb downwards, having a paper 
funnel tied round the open end of the tube, into which 
pour some mercury, and let the bulb of the instrument be 
held again over the lamp ; the mercury will boil after a 
time, and as it rises will carry up with it the small quan- 
tity of air remaining in the bulb. As it cools down again, 
the mercury in the funnel will fill the instrument ; and 
when it has cooled down to the highest temperature it is 
intended the instrument shall range to, the end must be 
closed by passing the flame of a blow-pipe over it, which 
process is termed hermetically sealing it ; and the only re- 
maining process is to graduate the tube. 



22 THE THERMOMETER. 

17. Method of graduating Thermometers. 
It was discovered by Newton tliat melting snow has in- 
variably the same temperature. If, therefore, the thermom- 
eter be plunged in melting snow, and a mark be made 
on it where the mercury stands, this will be one fixed 
point for all instruments, and is called the Freezing-point. 
Again, distilled water boils, under a given atmospheric pres- 
sure, at a certain temperature ; let, therefore, the instru- 
ment be placed in boiling water when the barometer stands 
at 30 inches, and let the stationary point of the mercury 
be observed ; this serves for another fixed point, common 
to all instruments, and is called the Boiling-point. The 
space between these two graduations is divided into a num- 
ber of equal and arbitrary parts, and the instrument re- 
ceives different names according to the number of the 
parts into which it is divided. Thus, if the space be di- 
vided into 100 equal parts, and the freezing-point be called 
0°, it is called a Centigrade thermometer ; if the freezing- 
point be called 0°, and the boiling-point 80°, it is called 
Reaumur's thermometer ; if, again, the freezing point be 
called 32°, and the boiling-point 212°, giving 180 equal 
divisions between these points it is called Fahrenheit's, 
and is the one commonly used in England. The gradua- 
tions, in every case, may be continued by equal divisions 
above the boiling and below the freezing point.* 

* 'To compare two differently graduated Thermometers. 

Let AD be a thermometer, having two dififerently grad- 
uated scales attached to it ; and let A, B be the boiling 
and freezing points respectively. Suppose the mercury 
in the thermometer to be standing at some point C. For 
the left-hand scale, let a°, &°, and a;°, be the graduations 
corresponding to those temperatures ; and for the right- 
hand scale, let c°, d^, y°, be the corresponding graduations. 
space CB x^ — a° 

Now, it is clear that gj^^ce AB ~ feO^aO 

space CB_y° — c° 
^^^ ^ace AB~do=cO 




}P_aQ d^—<P 



LAWS OF HEAT. 23 

18. On the Laws of Cooling of Hot Bodies. 

When hot bodies cool down, the process is said to take 

place according to one or more of the three following laws : 

Conduction, Convection, and Eadiation. Sometimes one 

and sometimes more of these are in operation ; and if a 

1. To compare Fahrenheit's and Reaumur's scales. 
If the left-hand represents Fahrenheit's and the right-hand Reau- 
mur's we shall have, writing F for ic° and R for y^ : 
F_32 R— 









212—32 


80—0 






••• 


F— 32 

180 


R 

"80 






or, 


F— 32 
9 


_R 

~ 4 


2. To compare Fahrenheit's with the Centigrade. 
As before, writing C for 3/°, we have : 
F_32 C— 
212—32 100—0 








F— 32 


C 



^^' "l80~~100 

F— 32_C^ 
~9~~ 5 
3. To compare the Centigrade with Reaumur's. 
C— R— 



Here we have 



or, 



or, 



100-0 80—0 

_C _ JR 

100~80 

JDR 

5"" 4 



To convert any number of Degrees in Reaumur^ s TJiermometer to 

the corresponding number in Fahrenheit's. 

If F be the number of degrees in Fahrenheit's scale, 

andR Reaumur's scale, 

- F— 32 R 

we have, as above — - — = — - 

9 4 

9 
or, F = 32 -f jR 

Hence : multiply the number of degrees according to Reaumur by 
9, and divide by 4, and to the result add 32 ; this will give the cor- 
responding number according to Fahrenheit. 



24 LAWS OF HEAT. 

body receive more heat from those substances which snr- 
round it than it imparts to them according to these laws, it 
gets warmer ; and, on the contrary, if it imparts more than 
it receives, it becomes cooler. 

19. On Conduction. 
When heat passes from particle to particle of a solid 
body, it is said to be conducted; thus, if a bar of iron be put 
into the fire, the heat travels from one end to the other by 
conduction. 



To convert any numher of Degrees Centigrade into the corresponding 
number in Fahrenheit's Scale. 

F — 32 C -rp Qo i_ 9 

Since, as before, — g— =^ . • . -^ — ^^"t ^-C 

Hence: multiply the number of degrees in the Centigrade scale 
by 9, and divide by 5, and to the result add 32 : this will give the cor- 
responding number according to Fahrenheit. 

To convert any numher of Degrees in Fahrenheit's Scale into the cor- 
responding Degree by Reaumur. * 

Smce ^ = f ••• E=|(F-32) 

Hence: from the number of degrees by Fahrenheit take 32, mul- 
tiply the difference by 4, and divide by 9 : the result is the corres 
ponding number by Reaumur. 

To convert any numher of Degrees in Fahrenheit's Scale into the 
corresponding number by the Centigrade Scale. 

Since ^-=? ••• C=|(F-32) 

Hence: from the number of degrees in Fahrenheit's scale take 32. 
multiply the difference by 5, and divide by 9 ; the result is the num- 
ber in the Centigrade scale. 

To convert from Reaumur's Scale to the Centigrade, and vice versd. 

Multiply the number of degrees in Reaumur's scale by 5, and di» 
vide by 4; the result is the number of degrees Centigrade. • 

Or, multiply the number of degrees Centigrade by 4, and divide by 
5 ; the result is the immber of degrees Reaumur. 



CONDUCTION. 



25 



20. Conducting Power of Substances. 
Many bodies conduct very badly; indeed, gases, and 
fluids, and earthy substances, scarcely conduct at all. If 
heat be applied to the upper surface of water, a thermometer 
at the bottom of the vessel will not be affected by it. As 
an mstance of the bad conducting property of water, we 
■may mention that when steam is first raised in a boiler, the 
hand may be applied to the lower part, although the tem- 
perature of the upper portion of the water is 240° or 250°. 
Water in the solid state, viz., ice, appears to have the same 
property; for, according to Dr. Sutherland, '4ce and snow 
conduct heat very slowly. If a piece of fresh- water ice be 
plunged into water after it has been exposed to a tempera- 
ture of — 20° or — 30°, it flies to pieces, in the same way 
that red-hot glass does when plunged into water ; and if 
water be poured upon ice, the same thing happens, and the 
crepitating sound is almost loud enough to resemble small 
explosions.""^ The non-conducting property of water must 
be \oTT\.Q in mind in the construction of steam-boilers. 
Metals are generally good conductors, though there is a 
sensible difference in their power in this respect. Thus, by 
Despretz's experiment, the conducting powers of some few 
substances will be represented by the following table : 



Gold . . . 


. 100- 


Tin ... 


. . 30-38 


Platinum 


. . 98-1 


Lead . . . 


. . 17-96 


Silver . . . 


. . 97-3 


Marble . . 


. . 2-34 


Copper . . 


. . 89-82 


Porcelain . 


. . 1-22 


Iron , . . 
Zinc . . . 


. . 37-41 
. . 36-37 


Brick Earth 


. . 1-13 



A knowledge of the difference in the conducting powers 
of substances is of great utility ; for by these means it is 
possible to keep any material hot or cold, at pleasure, for 
a considerable time. If the source of heat be internal, and 

* Dr. Sutherland's Jourrial of Captain Penny's Voyage in 1850- 
51, vol. i. p. 498. 



26 COXDUCTIO^T. 

we wisli to keep it warm, it must be cased in some non- 
conductor, such as flannel or felt, or swan-down, or the 
shaggy skin of beasts, which has originally been adapted 
to the wants of animated beings by the Creator. On these 
accounts we cover our bodies with woollen clothes in winter, 
and cotton or linen in summer ; steam-cylinders also, and 
boilers and steam-pipes, are frequently coated with felt or 
wood, because they are bad conductors. Porous substances 
are generally bad conductors ; and this may probably be 
the reason a layer of snow is so effective in preserving the 
temperature of the ground. Earthy matter conducts so 
badly, that at any sensible depth below the surface of the 
ground the temperature is nearly uniform ; and, in conse- 
quence, wine is placed in underground cellars. It is sup- 
posed by some that the central portion of the earth, to 
within about twenty miles of the surface, has a temperature 
greater than that of molten iron, the intense heat of which 
is prevented from making its escape by the non-conducting 
properties of the outer crust. . 

21. Our Sensations serve hut very imperfectly to measure the 
Temperature of any Substance. 
Good conductors feel hotter or colder than bad conduc- 
tors of equal temperature, according as their temperature is 
ibove or below blood-heat, because they are more ready to 
give out or absorb heat ; thus, if a piece of iron and a piece 
of wood be exposed to the influence of the atmosphere, the 
iron will feel much hotter than the wood when both are 
exposed to the meridian sun, while it will appear to be 
colder than the wood at midnight. 

22. On Convection. 
Liquids and gases, being bad conductors, transmit heat 
by convection, which 'process may be explained as follows : 
If heat be applied to the low^r particles of a fluid mass, it 
will cause them to expand, and therefore their specific 
gravity becomes less than that of the upper strata ; conse- 



CONVECTION". 27 

quently a displaeement of the particles ensues, the lighter 
rise to the surface and are replaced by the heavier ones, 
which in their turn become heated and are replaced by the 
others, and so by this process the heat is conveyed through- 
out the general mass. The-same principle applies to gases. 

23. The Advantages to he derived from a Knowledge of the 
Law of Convection. 
In apparatus for boiling fluids, the fire should be applied 
as low down as possible ; the surface exposed to the fire 
should be large, and there should be a facility for the heated 
particles to rise to the surface. This principle also explains 
the whole theory of ventilation. If we confine air in a close 
vessel, and apply heat to the lower strata, a continual in- 
terchange will take place ; but if we make two orifices, one 
in the lower part of the vessel and another in the upper, 
the heated air will escape at the higher orifice, and its place 
be supplied by that which enters at the lower one, and a 
continual draught be produced through the vessel. Hence 
it follows that a tall upright shaft produces a violent cur- 
rent of air through a furnace. Yet there are limits to the 
practical application of this principle, from the cooling of 
the upper portion of the column, and from the friction of 
the air against the sides of the shaft. The wind-sails of a 
ship afford an instance in which the law of convection is 
made available for ventilation ; we may also mention the 
casing placed round the funnel of a steam-boiler to prevent 
its burning the deck. There would be no advantage from 
this casing if the air were confined between it and the fun- 
nel ; but the top is open, and the casing is pierced with 
holes below the deck, whereby the warm current of air 
from the top of the boiler and engine-room enters, and by 
continually ascending is dissipated in the atmosphere with- 
out becoming very hot. The fire-doors of steam-boilers 
would become red-hot were it^not for a similar contrivance. 
At the back of the fire-door is a plate, separated from the 
former by an interval of two or three inches ; and the fire- 



28 CONVECTION. 

door is perforated, so tliat a current of air can enter between 
tlie two plates of iron, and prevent over-heating. Smoke- 
box doors are fitted in a similar way, tbe air entering ronnd 
tlie edges of tbe doors. 

The principle of convection enables practical men to 
ventilate mines and ships (especially steamers), and all 
places open above, which it may be desirable to keep at a 
tolerably low temperature, by means of partitions not reach- 
ing to the bottom. There is seldom exactly the same tem- 
perature in the two compartments ; and as the heated air 
in the one ascends, its place will be supplied by cold air 
descending down the other compartment, and going under 
the partition where the air would otherwise be stagnant. 
Any one may try this by putting a light at the bottom of 
a tall upright jar, which will be extinguished for want of 
oxygen ; but if the experiment be repeated after a partition 
has been inserted to within an inch or two of the bottom 
of the jar, and the light be placed a little on one side, it 
will burn as vigorously as ever. This principle was first 
introduced by Captain Priest, K. IST., for the purpose of 
cooling the stoke-hole, and has since been adopted success- 
fully in many instances. 

24. Explanation of some Phenomena depending on the Law 
of Convection. 

All the oscillations and disturbances of the atmosphere, 
whether regular or irregular, such as winds and tempests 
of all kinds, are produced by the shiftings of the atmo- 
sphere in consequence of the changes of temperature. A 
portion of the air, from the long-continued action of the 
sun in some localities, gets into motion ; and as it moves 
in any direction, its place is supplied by that which is 
cooler. The laws regulating these phenomena are, from 
the circumstances of the case, very complicated ; but they 
are all resolvable into this one law of convection, as the 
simplest assignable cause. In one instance (that of the 



- RADIATION. 29 

winds) tlie results are sufficiently regular to form a beauti- 
ful exemplification of the law. They may be briefly ex- 
plained as follows : The intense action of the sun at the 
equator causes a vertical ascending current in the tropical 
regions, and consequently there is a rush of air from the 
temperate zones to supply the place. If, then, the earth 
were stationary, it is manifest there would be a north wind 
blowing in the northern zone, and a south wind in the 
southern zone ; but each portion of the earth's surface has 
a greater linear velocity as we proceed from the pole to 
the equator, on account of the increase in the distance be- 
tween the meridians ; it follows hence, that the breeze 
which would be north or south, not having the same mo- 
tion to the eastward as the earth has, being always met by 
the earth in its rotation, appears to come from some point 
of the compass between the north and east or south and 
east. Hence the northeast trades in the northern, and the 
southeast in the southern hemisphere. 

25. On the Law of Radiation. 
By radiation a hot body gives out its heat just as a lu- 
minous body gives out its light. Although the rays of heat 
are not visible to the eye, they are sent out in every direc- 
tion in straight lines, becoming more and more faint as the 
square of their distance increases ; thus the effect of radiant 
heat is one-fourth at a double distance, one-ninth at three 
times the distance, and so on. From the want of econ- 
omical arrangement in common fire-places, radiant heat is 
nearly all that comes into a sitting-room. 

26. To show on what the Radiating Power of Bodies depends. 
The radiating power of bodies depends principally on 
the nature of the surface. Those bodies whose surfaces 
are rough radiate most, and polished substances radiate 
least ; also, dark substances radiate more readily than light- 
colored ones.* We have before stated, that if a steam- 



* Recent experiments, however, seem to throw doubt on the mflu- 
ence exerted by color on the radiating property of bodies. 



30 RADIATION. 

pipe or cylinder be coated with felt; it will diminish, the 
conduction ; but let us suppose a portion of the heat to 
have reached the outer surface of the felt, then, from its 
roughness, heat would readily escape by radiation. To 
prevent radiation, therefore, we should coat the felt with 
canvas, and paint it ; the varnish of the paint will give a 
smooth outer surface, and will diminish the radiation. 
Meat-covers, metal tea-pots, and other articles of domestic 
use that are intended to retain the heat, should be well 
polished, to carry out more fully the object for which they 
were made, as well as from motives of cleanliness. 

27. On Sea and Land Breezes. 

After sunrise, the land receiving heat by radiation from 
the sun much faster than the water, the temperature of the 
land may in time equal, and afterwards exceed, that of the 
sea ; the particles of air immediately in contact with the 
land, receiving heat from it, will expand and rise, whilst 
the cooler air over the water, rushing in to supply its 
place, will in turn be heated, expand, rise, and a current 
of cool air from the sea to the land will take place. The 
breeze thus produced in the early part of the day, so com- 
mon in the tropics, is called the sea-breeze. 

In the afternoon, the heat radiated by the sun to this 
part of the earth diminishes ; but the temperature of the 
land will rise until the heat it thus receives equals that it 
loses by its own radiation, and that carried off by the air 
(by convection) ; and when it shall have reached its maxi- 
mum temperature, from this time its temperature will 
begin to fall. It is evident that the time of maximum 
temperature of the sea will be after that of the land ; and 
since it also loses its heat much slower in proportion, from 
the time the land has obtained its highest temperature, the 
temperature of the land and sea will rapidly approach and 
become equal, and at length the sea will have a higher 
temperature than the land, when a current of air from the 



CAPACITY FOR HEAT. 31 

land towards the sea will take place, in a similar manner 
to tliat\bove described. This will be in the evening, and 
is called the land-breeze. 

28. Ga^pacity for Seat. 
It appears that althongh bodies have the same degree 
of temperature, yet it does not necessarily follow that they 
have the same amount of absolute heat ;. that is to say, it 
will require more fuel to raise the temperature of one body 
one degree, than it will to raise an equal weight of another 
body one degree. Thus the capacity for heat of water is 
much greater than that of iron ; in other words, it requires 
much more heat to produce a given sensible effect on a 
mass of water than it will on a mass of iron of the same 
weight. The quantity of heat required to raise a given 
lueight one degree is called its Capacity for heat. 

29. Unit of Caloric. 

Some standard of comparison must be adopted as the 
measure of the quantity of heat, and the quantity sufii- 
cient to raise the same weight of distilled water one degree 
is generally chosen. Thus if it take one-tenth as much 
fuel to raise the temperature of a pound of iron one degree 
as it does to raise the temperature of a pound of distilled 
water one degree, the capacity for heat of iron is said to 
be -1.^ (See Table E in Appendix). 

* Let w be the weight of one body ; t its temperature ; c its capa- 
city for heat ; .; 

w' the weight of another body ; t' its temperature ; c' its capacity 
for heat. 
Then, by definition, c will raise the weight 1, one degree. 

.•.wc w, one degree. 

and w ct w,t degrees. 

.'.w ct expresses the quantity of heat in the first body. 
Similarly w'c'V expresses the quantity of heat in the second body. 
.-. the whole quantity of heat in them, if they were mixed, would 
h^wct-\- w'c't'. 

Let now T be the common temperature after mixture ; 
3 



82 LATENT HEAT. 

30. On Latent Heat. 
Def. — Heat is said to be latent when its effects are not 
sensible to tbe hand or to the thermometer. 

31. Under what circumstances Heat becomes Latent. 

Heat becomes latent whenever a change of state takes 
place ; for in such cases the heat is employed solely in pro- 
ducing the change, and has no effect in raising the tem- 
perature : thus when ice thaws, or when water is converted 
into steam, the temperature is unaltered during the pro- 
gress of this change. For instance, let a piece of ice at 
32° be placed in a plate in a warm room ; the heat of the 
room enters into it, and it begins to melt ; so that when 
nearly all is melted, it must contain more heat than it did 
at first ; but until all the ice has. disappeared the tempera- 
ture will be found to be only 32°, exactly what it had be- 
fore. Again, when water has been raised to the boiling- 
point (212°), it requires about five times as much heat to 
convert the boiling water into steam as it did to raise it 
from the freezing temperature to the boiling ; the latent 
heat of steam is, therefore, about 1000°. 

On the other hand, if a vapor be converted into a liquid, 
or a liquid into a solid, the latent heat becomes again sen- 
sible ; thus it will require very much more cold water to 
condense a given weight of steam at the temperature 212° 
into water at temperature 100°, than it will to cool down 
the same weight of boiling water, of like temperature, to 
100°. 

This latter statement is of importance in condensing 

.'. w cT -\- w'c' T also expresses the amount of heat in the mix- 
ture. 

Hence 'wct-\- w'c't' =^wcl^ ■{- w'c' T. 

Cor. — If different weights of the same substance are mixed, c' = c\ 
and the formula becomes, 

wct-\-'w'ct' =^-0)0 1 -\- lo'cT 
or, wt-\- w't' = t/; T -f- i^ T. 



EFFECTS OF HEAT. 33 

engines, and accounts for the great quantity of water re- 
quisite to condense the steam."^ 

32. Heat is the sole Agent in the Liquefaction and Vaporiza- 
tion of Bodies. 

We can easily convince ourselves that heat is necessary 
to liquefy and vaporize bodies ; for we may take a lump 
of ice and pound it till it be reduced to dust, yet, unless 
heat be applied, it will never be liquefied ; we may, there- 
fore, regard solids, liquids, and gases as substances differing 
from each other only in this, that the one contains heat suf- 
ficient to preserve it in the fluid or gaseous state, which the 
other does not possess. It is true that many bodies have 
never been found in more than one state, and no means have 
been devised to make them alter that state ; but yet again 
many, which till within the last few years were considered as 
'■permanently fixed, have been made to take up the three dif- 
ferent grades. As an example, we may mention carbonic- 
acid gas, which has lately been made to assume the liquid 
and even the frozen or solid form. Mercury generally 
exists as a fluid metal, but it becomes solid at — 8 8*2 Fah- 
renheit, and vaporizes at 600° F. Water becomes solid 
when reduced to 32° F., and, in the open air, boils at 212° 
F. Hence we may conclude, that solid bodies remain in 
that state till they arrive at a certain fixed temperature, 
which is invariably the same for the same substance ; after 
which melting commences ; and also that a liquid will, by 
increase of temperature beyond a certain degree, be con- 
verted into gas. 

* Let w be a given weight of steam ; t its temperature ; 
w' the weight of water to be mixed with it ; t' its temperature ; 
and let L = the latent heat of the steam; 

T = the temperature of the mixture. 
Then the case is similar to what it would be if water of tempera- 
ture L-f- ^ were mixed with water of temperature V. Hence the for- 
mula before proved will apply, and we shall have 
w{'L-\-t)-\-w't'--:^\vT-\-iv"\l. 



84 CALOEIMETER. 

33. The Calorimeter. 
To measure the amount of heat contained in any body, 
Lavoisier invented an instrument called the calorimeter. 
Its principle consists in an attempt to ascertain the exact 
amount of ice at 82° that th.e body will melt ; and the only 
difficulty experienced is in preventing any of the ice from 
being melted by any extraneous causes, such as th.e beat 
imparted by the atmosphere, etc. To attain this object, 
imagine two similar cup-shaped vessels, eacb of wbicb is 
furnished with a cover, the one contained within the other, 
with a hollow space between them ; and let this hollow 
space be filled with ice broken into small fragments and 
packed into the hollow, so as to form a complete envelope 
to the inner vessel. Then it is clear tbat if a pipe be fitted 
to the lower part of the outer vessel, and furnished with a 
stop-cock, the inner vessel will, so long as any of ttie ice 
remains, never surpass 82° ; for so soon as the temperature * 
rises above that, the ice will melt and the water formed 
escape through the pipe, carrying off the beat with it. We 
may, therefore, suppose the effects of the external air and 
other disturbing causes annihilated. Again, let the ice 
(minutely pounded) to be melted by the warm substance 
be placed in the inner cup, leaving a space in the interior 
for an iron net Avhich is to contain the body to be experi- 
mented on. The inner cup has likewise a pipe and stop- 
cock similar to the outer one. After fitting on the covers, 
the interior will, after a greater or less interval of time, 
have arrived at 32°, and in so doing will have melted a 
certain amount of the ice, which will flow ou.t of the tube 
into a vessel prepared to receive it. When the water ceases 
to flow, let the body to be experimented on be placed in 
the iron net, and the communication with the external air 
suspended, as before ; then a certain amount of ice will be 
melted by this substance, which must be carefully weighed, 
and thus we shall obtain a measure of the quantity of heat 
contained in a body on cooling down to 32°. 



. SOUKCES OF HEAT. 35 

84. On the Sources of Heat 
The principal sources of tieat are the solar rays, mechani- 
cal operations, and chemical combinations ; and of these 
the most important for our consideration are those arising 
from mechanical operations and chemical combinations, the 
latter of them giving rise to the class of phenomena in- 
cluded under the term combustion. 

85. On Heat generated hy Mechanical Operations. 

Heat may be generated by the friction of solid bodies 
against each other. This is the cause of much annoyance 
to the engineer. If, for instance, the bearings of an engine 
be screwed down too tightly, they will soon become very 
hot ; the heat will in its turn expand the masses of metal 
in contact, and the evil will be increased. A very serious 
difficulty arising from the same cause, presented itself in 
the early days of screw propulsion. The screw-shaft must 
press against what is called the pushing-post with the whole 
force necessary to propel the ship ; and, on account of the 
great velocity of rotation, the heat thus generated has been 
so great as to set fire to the wood in its neighborhood, and 
in one or two instances to cause the end of the shaft to be 
firmly welded to the plate against which it is pressed. 
Sudden percussion will also generate heat : thus a bar of 
iron may be made red-hot by hammering it ; and if a quan- 
tity of air be suddenly compressed, the heat developed will 
ignite tinder. 

86. On Combustion. 

Under ordinary circumstances, combustion means the 
cher^ical union of a combustible with ox3^gen at a suffici- 
ently high temperature. Thus three things are necessary 
for the combustion of fuel ; for, in addition to the fuel 
itself, it must be supplied with a sufficient quantity of oxy- 
gen, and the temperature must not be beloAV a certain 
amount. The oxygen is usually supplied by the surround- 
ing atmosphere, but in certain cases artificial means are used 



86 coMBusTio:s". 

to increase the supply. Thus the Bude light is fed by pure 
oxygen independently of the atmosphere ; and to supply 
what are called blast-furnaces, the air is driven into the 
fire by fans. This latter process is adopted in our steam- 
ships of great draught of water ; the air not coming down 
the hatchways rapidly enough, the fires would burn lan- 
guidly were it not for fans worked by the engines. Secondly, 
a combustible is required. Now the goodness of any spe- 
cies of coal or wood depends on the amount of combustible 
in any given quantity. By referring to the tables in the 
last chapter containing the results of the experiments on 
coals made by Sir H. de la Beche and Dr. Playfare, we see 
that coal is composed of the folloT\dng chemical substances : 
carbon, hydrogen, nitrogen, sulphur, oxygen, and ashes. 
Of these substances, carbon and hydrogen are called the 
combustibles, and by their chemical union at a high tem- 
perature with the oxygen of the atmosphere combustion is 
effected and heat generated. 

87. On the Temperature necessary for Combustion. 
It is true that combustible substances will unite with 
oxygen at all temperatures ; but that union is effected so 
slowly at low temperatures, and the heat developed so slight, 
that for all purposes for which fuel is required, it is so 
minute that it may be considered not to exist in a practical 
sense. It must not, however, be entirely unnoticed ; for 
it is owing to this chemical change that coals become de- 
teriorated by exposure to the open air, and this change is 
facilitated by the action of the sun and rain ; in the latter 
case the oxygen of the water supplying the place of that 
from the atmosphere. Spontaneous combustion also is 
owing to the same cause. Let us suppose a quantity of 
damp coal shut up so that any heat which may be gener- 
ated will not be able to escape readily. The water becom- 
ing decomposed into its two gases, oxygen and hydrogen, 
the oxygen imites with the carbon of the coal, and a 



OXIDATION. 87 

slight development of lieat is the result. The heat thus 
developed fosters the same process between other particles 
of carbon and oxygen, and the combinations proceed with 
increasing rapidity, the temperature at the same time rap- 
idly increasing till the coal becomes red-hot ; and in addi- 
tion, a considerable quantity of hydrogen, which was one 
of the ingredients of the water before its decomposition, 
is contained within the mass ; this is another combustible 
substance, ready to burst into a blaze as soon as, in endeav- 
oring to put out the fire, an opening is made for the atmo- 
spheric air. The same explanation will serve for the heat- 
ing, smoking, and, lastly, ignition of hay -stacks, if put to- 
gether damp. It is only, however, at an elevated tempera- 
ture that a common fire burns ; and if from any cause tbe 
temperature of the surrounding substances be lowered, the 
fire will cease to burn briskly. For this reason the air is 
frequently heated before it is allowed to enter a furnace ; 
and from want of attending to this fact, common fires are 
often extinguished by putting on too much, coal when 
they are low. 

38. On Oxidation. 
"When speaking of combustion, we stated that it re- 
sulted, properly speaking, from the union of some sub- 
stance, called a combustible, with, oxygen at a sufiiciently 
high temperature ; and that a chemical union frequently 
takes place without the sensible development of heat, 
when the temperature is not higb enough, for combustion. 
In this latter case the substance, whatever it may be, is 
said to be oxidated. The baser metals rapidly tarnish or 
waste away from this cause when influenced by air or 
water, each of which contains oxygen. Most metals get 
coated with a film of oxide, which serves to preserve them 
from further deterioration; but this is not the case with 
iron, which wastes away because the oxidation or rust does 
not adhere to it. 



38 GALVANIC ACTIOX. 

39. Effects of Galvanic Action. 
It is generally known tliat wlien two different metals are 
in contact, under such circumstances that each of them 
would ordinarily become oxidated, the fact of their being 
in contact produces a very marked difference in the effect 
of the action of the oxygen upon each of them. This is 
due to what is called Galvanic Action, into which it is not 
our province to enter ; but we will confine ourselves to the 
consideration of the results. One of the metals will oxi- 
date much more rapidly than it otherwise would, and, on 
the contrary, the other will be partially or entirely pro- 
tected. Cases of this kind are of daily occurrence. For 
instance, if iron railings be fitted in lead and exposed to 
the damp atmosphere, the lower ends,' which are in con- 
tact with the lead, will rapidly waste. If brass hinges be 
fixed with iron screws, the heads of the screws will begin 
to rust in a few hours. To prevent the injurious effects 
arising from this cause, screw-shafts are cased with brass ; 
otherwise, from being in contact with the ship's copper, 
they would be soon unserviceal^le. It ought also to be 
stated, that the same effect will take place when portions 
of the metals only which are in contact are immersed in a 
fluid, as is seen in the case of the iron-work of paddle- 
wheels, which rapidly wastes where not coated with paint 
or tar, although the connection between them and the cop- 
per must be traced by going from them to the engines, and 
thus to the ship's copper. Copper pipes are at times 
secured together by iron bolts and nuts, which are soon de- 
stroyed if acted on by bilge-water. The following list 
will be found of some service, showing the relative elec- 
tro-chemical position of the metals in comijion use to each 
other: 

Electro-negative. 

Gold. 

Platinum. 

Mercury. 



BOILING-POINT. 89 

Silver. 

Copper. 

Tin. 

Lead. 

Iron. 

Zinc. 

Electro-positive. 

Eacli of these metals is electro -negative to all those tliat 
follow it, and consequently if any one of them be placed 
in contact with any one standing below it, and placed in a 
fluid; the lower one will oxidate and the upper one be pro- 
tected. ThuS; if lead and iron be in contact, the lead will 
be protected and the iron will waste ; if iron and zinc be 
in contact, the iron will be protected and the zinc will 
waste ; and the further apart the metals are in the above 
scale, the more active the influence will be. It was this 
which induced Sir H. Davy to recommend zinc as a pro- 
tector to the copper sheathing of ships. Muntz's metal for 
sheathing is composed of copper and zinc combined in the 
sheet itself, and is less rapidly corrosive than the copper 
would be by itself 

40. On the Boiling Temperature. 
Each liquid, when heated in the open air, has a certain 
fixed temperature at which ebullition commences. This 
temperature is called the boiling-point of the substance. 
Liquids which boil at a low temperature are called " Vola- 
tile." (For boiling-points of various liquids see Table B, 
in Appendix.) 

41. Boiling-point influenced hy Pressure. 

In the last article, where it was stated that each liquid 

has a certain fixed boiling-point, it was supposed that 

ebullition would take place in the open air, and that the 

pressure of the atmosphere remained the same. If, how- 



40 VAPOR. 

ever, tlie elastic pressure vary, tlie boiling-point will vary ; 
consequently, even in cases where fluids are boiling in tlie 
open air, the temperature at wbicli ebullition commences 
will vary slightly with the state of the weather, being 
higher or lower according as the barometer rises or falls. 
If a vessel containing warm water be placed under the re- 
ceiver of an air-pump, and the superincumbent atmosphere 
be partially removed by exhaustion, the water will com- 
mence boiling, and will continue to do so if the steam be 
pumped away as fast as it is formed. The boiling-point of 
water may be lowered about 140°, if it be relieved of the 
pressure. On the other hand, if the pressure be increased, 
the temperature will rise above what is called the boiling- 
point before ebullition commences. Table A gives the 
boiling-point of water for the various pressures. We can 
easily infer from that table, that at the pressure of the 
atmosphere (14f lbs. per square inch), the boiling-point is 
212°. 

42. On the Temperature of Steam. 
While any gaseous fluid, such as steam, is in contact 
with the water from which it was formed, their temperatures 
are the same ; so that the temperature of steam in a boiler 
is the same as that of the surface-water within the boiler ; 
but it is evident that, after they are separated from each 
other, the temperatu.re of either may be altered without af- 
fecting the other. If, however, an attempt be made to raise 
the temperature of the water, more steam will be formed ; 
and if, on the contrary, the temperature of the steam which 
has been cu.t off from the boiler be lowered, condensation 
will take place. *v 

43. Vapor. 

Yapor is identical with steam, but it is usually applied 

to that portion of the fluid which gradually and insensibly 

makes its escape whenever it is exposed to the open air, or 

in any room in which the atmosphere is not saturated with 



DEW. 41 

moisture. Air at a certain temperature is capable of sus- 
taining a certain quantity of vapor in solution, and the 
higher its temperature the more vapor it will absorb ; there- 
fore, if we expose a quantity of water to the air, we find it 
gradually waste, although we do not see the process going 
on ; and if allowed to stay long enough, the water would 
disappear altogether. 

4A. Explanation of the Formation of Dew. 
We have said that the atmosphere consists of a mixture 
of air and vapor, and that the quantity of vapor held in 
solution depends on the temperature. If, then, a portion 
of the atmosphere, already saturated with moisture, be 
chilled by a cold body coming in contact with it, the vapor 
will be precipitated on the cold substance in the form of 
globules. This will take place in a crowded room, where 
the moisture may be seen, from this cause, running down 
the walls ; the same may frequently be observed when a 
goblet of cold water is brought into a warm room.* The 
term dew, however, is applied to the same effect when 
taking place in the open air. 

45. On the Causes influencing the Formation of Dew. 
The principal cause of dew is the radiation of heat from 
the earth's surface ; this goes on much more freely in the 
summer time than at any other season, and in warm climates 
especially, which accounts for the heavy dews in the tropics. 
If any screen be interposed between the ground and sky 
the radiation is stopped, and any further formation of dew 
on that spot is prevented ; hence on a cloudy night there 
is no dew ; also, if a handkerchief be spread above the 
ground there will be no dew below it. This has led to the 
erroneous opinion that dew falls like rain. For instance, 

* Iron is said to sweat when moisture is precipitated on it from the 
air in this way. Complaints have been made against iron ships on 
this account. 



42 STEAM. 

the deck of a ship in tropical climates will be covered with 
dew, except on those places where the guns and • other 
bodies are placed, while the upper surface of the guns, etc., 
will be covered. Indeed, all the appearances are similar 
to what they would have been if the dew had descended 
through the air, and had fallen on the ship ; but such is 
not the case ; there is no dew beneath the gun, because the 
air there is not sufficiently chilled, the deck retaining its 
warmth. There is but little dew on those nights when 
there is any wind ; for a breeze will carry off the particles 
before the cooling process has advanced so far as to allow 
of the deposition. The formation of dew is a manifest pro- 
vision by which plants are enabled to exist during dry 
weather. Parasitical plants, such as the ivy, that have but 
small roots, are able to feed themselves freely by the pre- 
cipitation of dew on their leaves, and they will appear green 
and flourishing even when vegetation that derives its mois- 
ture from the earth is languishing. 

46. To distinguish hetween Vapor and Steam. 
Yapor is formed only from the surface, steam from the 
hody of a liquid. Evaporation proceeds at all temperatures ; 
steam is only formed when the fluid has arrived at a certain 
fixed temperature. The formation of steam is a violent pro- 
cess ; the formation of vapor is gradual and insensible. 

47. On the Formation of Steam. 
When a fire is placed under a boiler containing water, a 
rapid interchange of the particles take place, the colder 
continually descending, and the hotter rising to the surface. 
This will go on for some* time, and may be easily observed 
by throwing into the water an insoluble powder having 
nearly the same specific gravity : the particles will then be 
seen to rise in a stream. After a while, small bubbles will 
be observed to form at the bottom of the vessel, and rise 
towards the surface ; these are particles of steam ; but they 
will not at first reach the surface, because they will be con- 



STEAM. 4b 

densed again before they arrive there : still they give out 
their heat to the general mass ; every instant the bubbles 
of steam become larger and more frequent, and soon the 
whole mass appears to be in violent commotion, and the 
steam escapes freely from the water. This fluid (steam) is 
very different in its nature from the water of which it was 
formed ; for while in this state it has all the properties of 
a gas. It will become more elastic by compression, and 
loses its elasticity by being allowed to expand. The elas- 
ticity is also influenced by heat, the same as other gases. 
While in this state it is perfectly invisible, unless on the 
point of condensing. Those who are conversant with 
boilers will not fail to have noticed that the steam in the 
upper part of the glass water-gauge is always invisible. 

48. Distinction hetiueen Steam and most other Elastic Fluids. 
Steam is readily converted into water by lowering its 
temperature; this is of immense importance in steam- 
engines made on what is called the condensing principle ; 
for when the steam has done its work, it is comparatively 
easy to get rid of it by the injection of cold water ; the 
space it will occupy is trifling compared with that which it 
had in a state of steam, and consequently there is but little 
resistance on that account to the return-stroke of the engine. 

49. On the Boiling-point of Fresh Water. 
The boiling-point depends on the pressure exerted on its 
surface ; for if this pressure be increased, the rising of the 
steam will be checked till the increased temperature gives 
it sufficient elasticity to make its escape. The temperature 
of fresh water when boiling in the open air is 212°, but, as 
before stated, it varies slightly with the state of the atmo- 
sphere ; or, in other words, with the height of the mercury 
in the weather-barometer. The temperature at which water 
boils under different pressures will be seen by referring to 
the Table of Pressures of Steam and the corresponding- 
Temperatures in the Appendix. (Table A.) 



44 DISTILLATION-. 

50. On the Temperature of Sea-water when Boiling in the 
O'pen Air. 
The temperature of sea- water when boiling in the open 
air is higher than that of fresh water, being about 213-2 ; 
indeed the boiling-point of water is increased by any sub- 
stance that enters chemically into combination with it : but 
the boiling-point is not altered by the introduction of par- 
ticles which are only held in mechanical suspension ; thus 
the boiling-point of muddy water is the same as that of 
pure water. 

51. Steam from Salt Water. 
The steam which is formed from sea- water is fresh, which 
is a point of much importance to the naval engineer ; for 
if a boiler be filled with salt water, the water will become 
more and more impregnated with salt, unless means be 
taken to get rid of the brine. When the boiling-point of 
tha water is raised to 215°, means should be used to pre- 
vent its increasing in saltness. 

52. The Process of Distillation. 
When it becomes necessary to separate alcohol from the 
water with which it is mixed, it is put into a vessel called 
a still, and the temperature is raised by means of a fire : 
but care is taken not to elevate it to 212°, because all spirits 
will boil at a much lower temperature than 212°, and there- 
fore it must be so contrived that the spirit may boil while 
the water is kept below its boiling-point, and is therefore 
quiescent. A pipe leads away from the top of the still and 
terminates in a worm, as it is called ; that is to say, a long 
spiral tube which winds about in a vessel of cold water, 
and the extremity is outside the vessel ; so that the steam 
of the spirit becomes chilled and condensed in its passage, 
and flows out at the open end. It must, however, be re- 
marked, that the spirit, in boiling, forcibly carries up with 
it some of the aqueous particles ; and hence, if it be thought 
advisable to get rid of these, the still is emptied of its water. 



PKESSUEE OF STEAM. 45 

and tlie spirit returned to it to undergo a repetition of tlie 
process, when more of the water is left behind, and it is now 
said to be double distilled. 

53. Peculiarity in High-pressure Steam. 
High-pressure steam does not scald a hand applied near 
the orifice from which it is issuing. This arises from the 
fact, that on its first escape it expands so rapidly that the 
heat becomes latent. 

54. On the Pressure of Steam. 
The elastic pressure of the atmosphere is 14*75 lbs. (or 
in round numbers 15 lbs.) per square inch ; and if steam 
have the absolute pressure of 15 lbs., it is said to be atmos- 
pheric steam, or steam of one atmosphere; if it have a 
pressure of 30 lbs. per square inch, it is called steam of 
two atmospheres, and so on. If we were to take away the 
safety valve from a boiler, the steam would be called atmos- 
pheric steam. 

55. On the Laws regulating the Pressure of Steam. 
When the steam is in the boiler and in contact with the 
water, it does not obey the law which regulates other elastic 
fluids ; but when separated from the water, while in the 
gaseous state, it does obey those laws : for when in contact 
with the generating fluid, the water and steam increase in 
temperature together ; but as the water gets hotter, it gives 
out more steam to add to that already formed, which mixes 
with it and keeps it at the greatest density it can have for 
its temperature ; but, on the other hand, the mass cannot 
be altered when it is cut ofl' from the boiler. 

56. Pressure of Steam when in contact with Water. 

No law has ever been discovered connecting together 

the pressure, density, and temperature of steam when in 

contact with the water which formed it, although tlie labor 

bestowed upon it has been very great ; but tables have 



46 PEESSURE OF STEAM. 

been formed from the results of the experiments of mem- 
bers of the Academy of Sciences and others, and empirical 
formulas have been proposed that agree with those tables 
sufficiently well for practical purposes. (See Table A in 
the Appendix.) One fact, however, is well established, 
viz., that the same temperature corresponds to the same 
pressure ; so that if. the temperature of the steam in a boiler 
is. known, the pressure can be ascertained from the tables, 
and vice versa. 

57. Pressure of Steam when not in contact with Water. 
Since this follows the same law as other gases, we must 
adopt the formulae used in those cases.* 

* On the Expansion of Steam and other Gases. 

Case I. — It has been found by experiments made by M. Regnault, 

1 
that all gases expand by heat v^ of their volume for each degree Fah- 
renheit, while their elastic pressure remains imaltered. 
Let, then, Yi be the volume of a gas at temperature t^ ; 
Va its volume at temperature ti. 
Hence, if its volume at temperature 0°=-= Y 

Y 

the addition of volume for one degree = -p^ 

Y 

and for t,, degrees = — X ^i- 

Y 

Hence the actual volume is Y+ t-.-^ x ti 

4:0 y 



= Y. 



459 + 2^] 



459 

Again, the actual volume when the temperature is t^ 

459 + ^3 



=Y. 

and therefore 



459 
Yi 459 + tr 



Y2 459-fif2 

Hence the following rule : Add the number 459 to each of the tem- 
peratures ; divide the one result by the other, and the quotient will 
give us the relation of the bulks which the gases will occupy without 
having their elasticities affected. 

Case II. — Again: it is a well-established fact, that so long as the 



PRESSUKE OF STEAM. 47 

In stating the pressure of steam in a boiler, the excess 
of that pressure above the atmosphere is usually given, and 
not its actual pressure. 

This is because it is what the gauge on the boiler for 
measuring the steam indicates, and it is this excess that 
gives the effort to burst the boiler. Thus when we speak 
of steam of 20 lbs. pressure, we mean steam whose absolute 
pressure is 20 + 15 = 85 lbs. nearly ; but since the external 
air acts with a pressure of 15 lbs., the effort to rend the 
boiler is only 20 lbs. 

58. On the Specific Gravity of Steam. 
The specific gravity of steam is mych less than that of 
the atmosphere, under similar pressures. At the tempera- 
ture 212° it is '4575, taking atmospheric air as the standard. 

temperature of a gas remains unaltered, its elastic pressure will vary 
inversely as the volume. 

If, therefore, M be the volume a gas occupied at a given tempera- 
ture, its pressure being pi, and N the volume at the same tempera- 
ture, its pressure being p^ ; then 

Hence the following rule : As the pressure px is to the pressure p^ 
so is the volume of the gas at the pressure pa to its volume at the 
pressure pi. 

Case III. — If, now, we have a gas at a certain pressure, volume, 
and temperature, and we wish to find what its pressure is when the 
volume and temperature are both changed, we must proceed as 
follows : 

1. Let the temperature alone be changed from ^i to t^, and let A 
and B be the volumes; then 

B _459-H2 
A"~459 + <i 

2. And having changed the temperature to t^, let the temperature 
now remain unaltered, while the pressure is changed from pi to pa by 
changing the volume from B to C ; then 

^-:=? ButB = ^^y:i'.A 
Pi C 4594- ^i 



jp2_A 459 \ t_ 
pi" "C '459 4-^1 



4 



48 SUPEIiHEATED STEAM. 

59. Common Steam. 
Steam when in contact with the generating fluid, or if it 
be' not heated after the separation has taken place, is called 
common steam. If we reflect on the mode of its production, 
we shall see that since, on receiving fresh accessions of 
temperature, additional particles of steam were invariably 
added to the previous mass, it will follow conversely, that 
directly the temperature is lowered, whether it be in contact 
with the generating water, or be shut up in the cylinder, 
or be in the steam-pipe, in any such case a portion of the 
steam will return to the liquid state. This forms what is 
called \h.Q jacket-water of an engine. 

60. Superheated Steam. 
If steam be heated after it leaves the boiler, it can evi- 
dently be cooled again to its original temperature without 
returning into the liquid state. When the temperature is 
thus raised, it is called superheated steam. Eecent experi- 
ments appear to show that great advantages, in an economical 
point of view accrue from superheating a portion of the 
steam that has .oeen generated by a boiler before it enters 
the cylinder. Under ordinary circumstances, when steam 
which is on the point of condensing comes into contact 
with the cylinder, a portion of it is converted into water, 
which is a manifest disadvantage and loss ; and this is ob- 
viated in the case of superheated steam, and consequently 
less wa-ter will be required from the boiler to fill the cyl- 
inder with steam. Suppose, for instance, that 1000 cubic 
feet of steam were required to fill the cylinder, and that 
1000 cubic inches of water were required to produce this 
amount of steam ; let us suppose further, that condensation 
takes place in the cylinder to the amount of 200 cubic 
inches of water; then in ordinary cases the boiler must 
supply 1000 -f 200, or 1200 cubic inches of water for every 
stroke of the piston ; but if the steam were superheated, 



ANALYSIS OF SEA-WATER. 49 

1000 cubic inches would suffice. An amount of fuel will 
therefore be saved which would be necessary to evaporate 
200 cubic inches of water; less feed- water also will be re- 
quired, and less injection- water to cool down the whole 
mass to 100°. The practical mode of carrying out this 
principle will be treated of in Chapter II. 

61. Analysis of Sea-water. 

The water of Kingstown Harbor, as tested by Mr. Mallet, 
was found to contain in 1 cubic foot, 12,661 grains of solid 
matter, which, analyzed with precaution, had the following 
constituents, reduced to per cent. : 

Chloride of sodium (or common salt) . .71*32 

Chloride of magnesium 10*79 

Bromide of magnesium 0*60 

Sulphate of lime (or gypsum) 4* 87 

Sulphate of magnesia 5*30 

Carbonate of lime (or chalk) 1'73 

Organic matter 5*27 

Loss 0-12 



100-00 



Of these the most injurious, as forming solid incrusta- 
tions within the boiler, are the sulphate of lime and carbo- 
nate of lime ; and the first-mentioned, namely, common salt, 
will accumulate in large quantities within the boiler, unless 
care be taken to remove it. The sulphates are, by their 
decomposition and re- arrangement with hydrogen, the 
cause of the offensive odor of bilge- water, which is o wing- 
to the presence of sulphuretted hydrogen. 

The specific gravity of sea-water = 1027*80 ; and ibo 
cubic inches of water, taken from the surface, contain in 
combination 1*43 cubic inch of gas, which consists of at- 
mospheric air with traces of carbonic acid. 



50 



ANALYSIS OF SEA-WATER. 



62. Tahle of the Amount of Saline Contents in 1000 parts of 
, Sea-water from different Localities!^ 



Arctic Sea . . 


. 28-30 


Black Sea . . 


. 21-60 


North Atlantic . 


. 42-60 . 


Baltic . . . 


. 6-60 


Equator . . . 


. 39-42 


Dead Sea . . 


. 885-00 


South Atlantic . 


. 41-20 


British Channel- 


. 35--50 


Mediterranean . 


. 39-40 


Irish Sea . . 


. 88-76 


Sea of Marmora 


. 42-00 







63. On the Quantity of Carhonic Acid in Sea-water. 
One thousand volumes of sea- water are stated, on the 
authority of Laurent, etc.^ to contain 62 volumes of car- 
bonic acid. 



* From the report of Mr. Mallet in the Transactions of the British 
Association, 1840, p. 223. 



CHAPTER II. 

THE BOILER. 

Steam being the motive power in all macliines called 
steam-engines, the supply must be obtained by boiling water 
in some vessel. This vessel is the boiler. 

64. Marine Boilers distinguished from Land Boilers. 

In land boilers the heated gases, after passing through 
the boiler, were formerly allowed to return along the out- 
side of the shell before entering the chimney ; but in marine 
boilers they must, for the safety of the ship, be kept within 
the flues or tubes, and these tubes must be enclosed within 
the shell of the boiler. 

Again, since the boiler is supplied with sea-water, con- 
trivances are necessary by which the salts that are left in 
the boiler as the steam escapes may be got rid of. In ad- 
dition to this, many operations must be regulated by hand 
which on shore would be accomplished by machinery con- 
nected with the engine itself. This will be necessary be- 
cause the water-level in the boiler does not preserve its 
horizontality, on account of the pitching and rolling of the 
ship. 

65. Gear connected with Boilers. 
It is very evident that steam, if allowed continually to 
collect in a vessel, without any escape being afforded to it, 
would at length produce most destructive effects, rending 
the containing vessel, and dispersing its fragments in every 
direction ; consequently these accidents must be provided 
against by fitting to each boiler 2l safety-valve, together with 

" 51 



52 THE BOILER. 

a mercurial column called the steain-yauge, by wliich the 
eye can discover the amount of pressure the boiler sustains. 

Again, the height of the water within the boiler is ascer- 
tained by gauge-cocks and glass water-gauges. 

Moreover, to prevent the external air from crushing or 
collapsing the boiler, valves, called reverse-valves, are fitted 
to the boilers of condensing engines. This apparatus is 
not, however, required for the boilers of non-condensing 
engines, on account of their extra strength. 

At the junction of the steam-pipe with the boiler there 
is a valve, called a communication or stop valve, for making 
free egress for the steam or stopping it, according as the 
valve is open or closed, and thus isolating one boiler from 
the rest when necessary.* 

And lastly, since the boiler is filled with sea-water, the 
earthy matter of which is constantly accumulating within 
it, there are pipes and cocks communicating with the sea 
for the purpose of getting rid of the brine, and called hloio- 
out cocks and pipes. 

In the front part of each boiler there are openings, about 
4 feet high, and reaching nearly down to the floor of the 
engine-room. These are divided into two parts, one above 
the other, by a series of bars sloping downwards, called 
fire-bars. That part of the fire-place on which the bars 
rest in front is the dead-plate, and sufficient room is left here 
for the bars to expand : the bars are usually in two lengths, 
and are supported by two cross pieces, one across the mid- 
dle of the fire-place, and the other at the farther end ; these 
are called hearing -hars. On these bars the fuel is placed. 
The portions of the orifices below these bars are the ash- 
pits, and those above it the fire-places or furnaces. The 
upper and lower part have their separate doors, called fire- 
places and ash-pit doors respectively. These openings go 
back into the boiler about 5 or 6 feet, where the fire-places 
cease. The currents of hot air from the separate fire-places 

■* Some old boilers have, however, no communication-valve. 



THE TUBULAR BOILER. 



53 



now unite into one space ; and the boiler is called a flue 
boiler or a tubular boiler, according to the construction of 
the passages of the heated air between the fires and the 
steam funnel. The heated air, after passing from the fire- 
places, has not yet been sufficiently robbed of its caloric to 
permit it to pass at once into the funnel; therefore, in flue 
boilers, it is compelled to take a circuitous path through 
the boiler in a passage called the flue, the water of the 
boiler surrounding this flue on every side. After winding 
backwards and forwards by these means, till it is supposed 
that the water will have absorbed all the heat, it then 
passes through the uptake into the funnel. This kind of 
boiler, called the flue-boiler, was generally used in her Ma- 
jesty's service till 
lately ; but within 
the last few years 
has given place to 
another kind, in 
which the gases, af- 
ter escaping from 
the fire, have to 
pass through a se- 
ries of small tubes 
before entering 
the funnel. This 
latter is called 

m. The Tubular 

Boiler. 

The accompany- 
ing diagram repre- 
sents a section of 
a tubular boiler, 
as they are made 
at Portsmouth. Here A represents the fire-place and H 
the ash-pit ; B is called the fire-box ; FED, etc., the 




64r 



THE BOILER. 



tubes ;* C the smoke-box ; Gr the uptake, wliicb is con- 
nected with the funnel. Between A and H are the fire- 
bars, sloping downwards towards the back of the boiler. 
The fuel is supplied at the opening I ; and the smoke from 
the fire enters B, then through the tubes FED; etc., into 
C, from whence it ascends to Gr, and so through the funnel. 
The accompanying Figure exhibits a transverse section 

of a tubular boiler. A 
B C are sections of the 
furnaces, the upper part 
of each containing the 
burning fuel, and the 
lower part being the ash- 
pit ; the ends of the tubes 
are seen above the flues. 
The same boilers have 
their tubes inclining 
slightly downwards to- 
wards the smoke-box. 
There seems to be some 
advantage from this ar- 
rangement ; for the heat- 
ed air, not having so ready a passage through the tubes, 
exerts its effect on the boiler longer than it otherwise 
would ; and the soot will not remain in the tubes so long- 
as it would if they were horizontal ; it will be partly blown 
out by the draught. 

The advantage gained by these boilers over the com- 
mon or flue boilers consists in the amount of surface in the 
series of tubes through which the heated air has to pass 
being much greater than that in the flue-boilers, when the 
sum of the orifices of the tubes is equal to a section of the 
flues.f The greater the amount of heating surface, the less 



O O 00 G OOO G OQ©a 
OOQOOOOOOOOOi 
GOOQGOGGGGGGG 
OOOOOOOGOGGGO 




* The tubes used in the Navy vary from 2 to 3 inches external 
diameter, 
t The advantage of small tubes over large ones in giving a greater 



NUMBER OF BOILERS. 55 

the quantity of water the boiler will have to hold. The 
use of a great quantity of water in the boiler consists in its 
acting as a reservoir of heat, and thus preventing the chil- 
ling effects that would otherwise result from the admis- 
sion of feed-water at each stroke of the pump. 

67. The Number of Boilers in each Steam-vessel. 
There are generally four or more distinct boilers in each 
steam-vessel of any magnitude, so that steam may be got 
from all or any according to the number of fires that are 
lighted. To enable them to act independently, each boiler 
is provided with all the gear it would have if it were alone ; 
but, generally speaking, the smoke and spare steam go into- 
only one funnel and waste-steam pipe. The steam from 
each boiler goes into one main steam pipe before enter- 
ing the cylinders ; and by means of the communication - 
valves, the connection which would otherwise exist between 
all the boilers may be suspended when the use of any boiler 
is not required. The boilers were usually four in number, 
and placed side by side, forming a square, having one 
stoke-hole forward, and the other aft ; but in the present 
arrangement they are separated, having one long passage 
amidships for the stoke-hole, the fire-places of the two sets 
of fires facing each other. The only objection to this plan 
lies in the difficulty of supplying the fires with fuel when 
working all the boilers. Probably the arrangement in the 

amount of heating-surface with the same opening for smoke, may be 
thus apparent: 
Let ' I = length of a tube ; * 

• r=its radius; 

71 = number of tubes ; 
the whole heating tube-surface = 2 n r Z X w ; 
and the volume for the heated gases to pass through = n r'ln; 
Let.*. S = 2 nrZn, and Y = 71 rZn 

r 
which increases as the radius of the tubes decreases, provided the 
space occupied by them is constant. 



f 
56 THE BOILER. 

Great Eastern is better, where the boilers are placed back 
to back ; tbe fire-places facing the coal bunkers. 

68. The Steam-chest. 

The space in the boiler above the upper surface of the 
water is called the steam- chest ; and this part of the boiler 
should be as large as it can be made, for with small steam- 
chests the pressure of the steam is continually varying : 
small steam-chests are for this reason a chief cause of pri- 
ming. Large steam- chests are also more economical in fuel. 
If the steam-chest be too small, it will become manifest in 
the oscillating motion of the steam-gauge. With small 
steam*chests the fires must be always kept in an active 
state, otherwise the steam falls. Some boilers show this 
defect very plainly : for want of a reservoir of steam, at 
one moment it is blowing off, and at another it is below 
the boiler-pressure. 

69. The Fire-hridgc. 

There used to be two kinds of bridges, one made of brick 
and the other of iron ; the latter is hollow, and contains 
water, and the upper edge is sloping, to allow the generated 
steam to escape. There are several advantages in brick 
bridges over those made of iron : they can easily be altered 
if necessary, or knocked away to carry on any internal 
repairs ; and if the fire-places are too long, they can be 
shortened. Again, if the tubes leak, the lower part of the 
flues will be filled with water ; which can easily be got rid 
of by knocking out a brick, and thus allowing it to escape 
by the ash-pit, instead of accumulating till it flows over 
the bridge. When boilers are fitted with bridges, they are 
now made of brick. A hole may, when the steam is down, 
be made through the iron bridge for the same purpose, 
and a tube inserted. The fire-bars are always inclined to 
the bridge at an angle inclining downwards, so as to facili- 
tate the stoking, and at the same time to diffuse the air 
better : the grate-surface is thereby likewise increased. A 



ASH-PITS. 



57 



hanging bridge has been fitted to some of tlie high-pressure 
boilers, to keep the tubes from clinkering up. 

70. Ash-pits. 
The ash-pits of most boilers are made with round bot- 
toms. They are consequently much stronger ; and as the 
steam is not pent up underneath them, they are not so liable 
to buckle up towards the fires. When the bottoms of the 
ash-pits were made flat, they were the weakest parts of the 
boilers, from the pressure of the steam and the great weight 
of the superincumbent column of watef . Since there is no 
angle-iron to round-bottomed ash-pits, they last much 
longer ; for dirt accumulates at the edges of the angle-iron, 
and occasions oxidation. 




71. Gun-loat Boilers. 
Fig. 1. 
Gun-boat boilers arc of a cylindrical form, of which Fig. 



58 



THE BOILER. 




1 represents a longitudinal, and Fig. 2 gives the transversal 
section. 

In these diagrams, A is the ash-pit ; B the fire-place or 
furnace, separated by the fire-bars, which slope downwards 
towards the bridge C ; E E E, etc., are the tubes conveying 
the heated gases into the smoke-box, F, which leads into 
the funnel ; H H the water-line ; all above this being the 
steam-space. The steam pipe I runs nearly the whole 

length of the boiler, within the 
steam-space of the boiler ; it is 
closed at the end, but slotted 
along the top to allow the steam 
to enter, and at the same time 
prevent priming. K is the ex- 
haust-pipe, which, in the case 
of high-pressure engines, leads 
from the engines into the fun- 
nel. A blast-pipe of a similar 
construction, and acting in the 
same manner, is fitted to all 
boilers. These two are separately treated of in the next- 
articles. 

72. Exhaust-pipe. 

This pipe serves to convey the steam from the cylinder, 
after it has done its work, into the funnel, as is shown in 
the last article. The force with which the steam issues 
from it drives the air before it, and creates a draught 
through the tubes. The end is contracted, as in the dia- 
gram, to increase the effect. 

78. Blast-pij)^. • 
This pipe leads from the steam- chest into the funnel, 
whereas the exhaust-pipe leads from the cylinder. It is 
fitted to all boilers, whether high or low presSute, but is 
only used wheH getting up steam or working at slow speeds. 
When used, the escape of steam is not intermittent, as in 
the case of the exhaust-pipe, but continuous. 



Fig. 2. 



FEED-KXGIXE. 59 

74. Feed or Donkey Engine. 

Tubular boilers contain so small a quantity of water in 
comparison of the flue-boilers, that the water above the 
tubes is apt to be soon evaporated, unless the supply be 
kept up continually. It becomes necessary, therefore, to 
have means of keeping up the supply of water to the boilers 
when the steam is up and the engine stationary ; for at 
such times the feed-pump is not at work. These boilers, 
therefore, are fitted with a small engine, for the express 
purpose of supplying the boiler with water while the 
engines are not working. 

In H. M. S. Ajax, a small engine, in addition to the aux- 
iliary engine, is .fitted to work a fan to ventilate the engine- 
room, and to exhaust the condensers, so as to keep them 
free from injection- water. This engine is supplied from a 
boiler of its own,* whereas the common auxiliary engine 
is supplied from the other boilers. 

75. Boiler Hand-pumps, x 
These are pumps worked entirely by hand in some ves- 
'sels; but in most vessels fitted with tubular boilers there 
are means of connecting them with the engines, so that, if 
the feed-pumps fail to supply sufficient water to the boilers, 
this pump can be set to work to make up the deficiency. 
It can also be made available for pumping the ship out, 
pumping water on deck, or pumping the boilers out when 
the ship is in port, if the steam does not blow out the boiler 
dry enough. Indeed, there is always some water left in 
the boiler from the condensation of the steam. This should 
be drained out by the hand-pump as soon as the boiler has 
cooled down ; for the particles of water dropping from the 
internal steam-pipe, and other metallic fittings, are impreg- 
nated with copper, and oxidate the lower parts of the boiler. 

* This engine will prove very valuable in putting out fire during 
an action, when perhaps the steam in the large boilers has been kept 
at reduced pressure. 



60 



THE BOILEK. 



Many of our readers may find it difficult to understand 
tow the same pump can be used to pump water into the 
boiler, and pump water from the boiler. The following 
explanation, with the help of the diagram, may make it 




intelligible. B is the pipe communicating with the sea, 
and A the pipe communicating with the boiler ; C is the 
pump (part only of which can be seen, the remaining part 
being behind the space B A) ; ha are two cocks, by turn- 
ing which the circular spaces surrounding them may be 
brought into the position they have in the figure ; D and 




E are two valves, between which is an opening to the 
pump-bucket G : this opening is represented in the figure 
by dotted lines. If we look at the arrows, which represent 
the direction in which the water is to pass, and suppose 
the valve of the pump to be raised, we shall perceive that, 
a vacuum being formed in the pump, the water will pass 
through the valve-passage at E and go into the barrel of 
the pump ; but that on forcing down the piston, this water, 
being sent back again, is forced through D in the channel 
.■narked by the arrows through the pipe A to the boiler. 



SAFETY-VALVE. ^ 61 

If the cocks h and a be turned into tlie position as repre- 
sented in tlie adjoining figure, the same explanation will 
show that water will flow from A towards B ; that is to 
saj, the boiler will be emptied. There are scores, or a slot- 
way, on the outsides, which may be seen at b and a, where 
the key for turning the cock is placed ; and these scores 
serve to show the engineer whether the cocks are properly 
set or not. 

76. The Safety-valve. 

The safety-valve derives its name from its office, which 
is, to open the communication between the boiler and the 
external air, when the internal pressure may be considered 
to have arrived at the limit the manufacturer intends the 
engines to work at, while it effectually closes that commu- 
nication so long as the steam retains a pressure that is 
below that limit. 

A circular orifice is made in the upper horizontal surface 
of the boiler, large enough to allow the steam to escape as 
fast ^s it is generated.* Upon this a valve is placed. This 
valve is weighted by hanging weights from it on a spindle 
within the boiler, or placing them upon a spindle outside 
the boiler. The weights must be arranged so that each 
square inch of the valve shall be kept down with the pres- 
sure the boiler is required to bear. Suppose, for instance, 
that it be desirable the boiler should not sustain a greater 
pressure than 7 lbs. ; in other words, that the pressure of 
the steam be not greater than (15 + 7) 22 lbs. ; we shall 
have to load the valve till the pressure on every square 
inch is 7 lbs. ; and the same rule will hold with all other 
pressures. As the safety-valve is supposed to be loaded as 
high as the manufacturer deems safe, it is clear the engineer 
should never trifle with it by putting on additional weights. 
Two valves are usually fitted to each boiler, that if one of 
them by any accident becomes fixed in its seat (or gagged, 

* It should, therefore, be in proportion to the heating-surface. 






62 THE BOILER. 

as it is teclinically termed), the other may allow a free 
egress to the steam, and prevent injury. K the orifices be 
not large enough, the steam* will accumulate within the 
boiler, and increase in density, till one of two events hap- 
pens : the pressure increasing with the density, the boiler 
will explode ; or, if the boiler be strong enough to sustain 
the increased pressure, as the density increases, the quan- 
tity of steam that escapes in a given time also increases, 
and at length it will find its exit as fast as it is generated. 
This explains a fact frequently noticed, that on stopping 
engines suddenly, when the fires are strong, the boiler- 
pressure, as exhibited by the steam-gauge, is considerably 
greater than that to which the valves are weighted. We 
observe this more particularly in those cases where tubular 
boilers have been substituted for the old flue-boilers, and 
the same safety-valves have been used. The pressure in 
man^ rases has been altered from 4 lbs. per inch in the 
old boilers to 14 lbs. or 16 lbs. in the new ones. We see, 
^h^erefore, hv^ '^^lary it isjihat the valve should be pro- 

portl led to the heating-surface. Sometimes the pressure 
will rise as high as a pound, or a pound and a half, alcove 
the greatest pressure as limited by the safety-valve. This 
is more likely to be attended with danger in tubular boilers 
than in the common flue-boilers, on account of their great 
evaporative power. Annular safety-valves are now some- 
times fitted, giving the same amount of egress for steam 
with a smaller opening. These valves are similar to the 
delivery-valve of annular air-pumps. 

77. On the Gear attached to the Safety-valve. 
It is necessary that the engineer, without leaving his 
station in the engine-room, should have the means of con- 
vincing himself at any instant of the good working condition 
of the safety-valve ; and to that end a system of levers is 
fitted, one extremity coming in front, and terminating in a 
handle within reach ; the other presses against the under- 
surface of the valve, but is not secured to it ; so that the 



4^ 



SAFETY-VALVES. 63 

engineer can, when lie pleases, press on tlie valve-spindle 
and raise it, and tlius determine whether it is in action : 
but this does not offer any obstacle to its free motion when 
forced up by the steam, because it can separate itself fro ; 
the lever when the pressure of the steam becomes suffici 
ently great. The spindles of the valves, and all the gear 
connected with them, require looking to occasionally ; fc- 
when iron spindles are employed they are apt to set fasL 
By means of these levers also the steam can be allowed lo 
escape from the boiler, when its pressure is not great 
enough to lift the valves ; as, for instance, when it is neces=- 
sary in harbor to do any thing to the boiler, which requirf • 
the pressure of the steam to be removed ; or in case of 
repair to the engine when no stop-valve is fitted. . 

78. Under what circumstances the Weights of the Safety-valves 
may he increased. 

They should not be altered unless it be sanctioned by 
proper authority ; and the only authorities to sanction such 
a step are the engine-makers. But there are many cases 
when such an operation would be highly adv£.ntu. jeous ; 
as, for instance, when chasing an enemy, when towing, or 
on a lee-shore ; because in either of these cases, if the vessel 
be fitted with paddle-wheels, the number of revolutions is 
sensibly diminished, and consequently the condenser would 
be able to maintain a good vacuum, although the steam 
were supplied to the cylinder of greater density. ' Under 
these circumstances, therefore, it would appear not impru- 
dent to intrust the engineer with certain weights, previ- 
ously supplied by the manufacturer, which he would be 
authorized to use under the sanction of his commanding 
officer. ' 

79. The Safety-valve Box, 

In the accompanying diagram C is the valve-box fitted 
5 



614 



THE BOILliR. 



to the steam-cliest E F, a 5 are two safety-valves seating in 

orifices opening into this 
box. The safety-valves 
are retained in their places 
by the weight's A and B 
attached to the valves by 
spindles. C D is the steam- 
pipe proceeding from the 
valve-box, and c ^ a is 
called the. drip-pipe, com- 
ing down by the side of 
the steam-pipe, for carry- 
ing away the condensed 

steam from the top of the steam-pipe. 




80. Waste-steam Funnel and Drip-pipe. 
The steam-funnel is an upright tube, by which the steam 
escaping by the safety-valve finds a passage into the open 
air. The lower part was shown in the previous figure. It 
is kept upright by i^tiys from the funnel; and to many of 
them there is fitted at the upper part a bulb, or steam-trap, 
serving to check the upward violence of 
the mud and water sent up from the 
boiler when priming takes place. A B 
is the steam-trap, into which the waste- 
steam pipe enters. The pipe is carried 
nearly through it, and has a hlanh top ; 
the steam, therefore, makes its way 
through orifices in the sides, as is shown 
by the arrows. Attached to the bulb is 
a small pipe B C, which passes down by 
the side of the waste-steam funnel, as in 
the previous figure, and through the 
ship's side, to carry off what has accumulated in the trap. 
This is called the drip-pipe. There is also another pipe 
(fg, Fig. p. 64) connected with the safety-valve box, which 




STEAM-GAUGE. 



65 



runs horizontally, and serves to carry off whatever may 
accumulate in the valve-box. This pipe generally dis- 
charges into the drip-pipe, so that one orifice through the 
ship's side suffices for both. Many steamers in the mer- 
chant-servibe, and a few in her Majesty's navy, have a pipe 
fitted to the boiler to blow off the steam under water when 
the vessel stops; and thus whatever comes up with the 
steam passes off by the same passage into the water, and 
is prevented from falling on the deck. In this case the 
steam-trap, or bulb, is unnecessary. The only objection to 
this arises from the violent noise and unpleasant tremulous 
motion caused by the sudden condensation of the steam on 
entering the water. These are now becoming obsolete. 

81. The Steam-gauge, 
The pressure of the steam within the boiler is ascer- 
tained by means of the steam-gauge. Imagine a hollow 
iron tube to be bent into the form of the letter (J , as in the 
diagram, very much elongated, the one 
end communicating with the boiler B, 
and the other C opening into the en- 
gine-room. This tube is partially 
filled with mercury. Now if the pres- 
sure of steam in the boiler be the same 
as that of the atmosphere, the mercury 
will stand at the same level in both 
legs, as at a c ; but as the .pressure in 
the boiler increases over that of the 
atmosphere, it forces the mercury 
down the leg A D, and it consequently 
rises in the other D C till the balance 
is restored. And since, if the legs be 
of the same bore, which is supposed to be the case, every 
rise of an inch in the one leg is accompanied with the de- 
pression of an inch in the other, therefore every rise of an 
inch shows a difference of level of two inches. But two 
inches of mercury correspond approximately to one pound 




QQ 



THE BOILER. 



pressure ; hence it follows that every inch that the mercury 
rises corresponds to an additional pound in the pressure of 
the steam. Now if the tube had been made of glass in- 
stead of iron, we might, by inspection, determine how high 
the mercury had risen ; but since this is not *the case, a 
small float d e rests on it, and having its upper end above 
the top of the tube, is pushed up by the force of the steam. 
The upper end of the tube is brought into contact with a 
scale of inches E F, and thus the number of pounds pres- 
sure becomes readily discernible. These gauges are valu- 
able in cases where the safety-valve does not act; for if 
the pressure be unduly increased, the mercury is blown 
out, and notice is given of danger. 

82. Steam-gauge for High-pressure Boilers. 
The mercurial gauge described in the last article is evi- 
dently not suitable for high- 
pressure boilers; for if, as an 
instance, the pressure of the 
steam were supposed to be 60 
lbs., the total length of the gauge 
would be 120 inches (or 12 feet). 
For this reason, a gauge which 
exhibits the effects of pressure 
on a thin plate of metal is adopt- 
ed, the principle and construc- 
tion being as follows : Let A B 
be a thin plate of corrugated 
steel, going across an orifice of 
the boiler, and therefore acted 
on by the steam-pressure ; to 
the middle of this plate let a rod 
a 6 be attached, the upper end of 
which is in connection with an 
extremely short bar h c. To the 
same bar is connected the rack 
fg, so that if the rod a J be pushed upwards by the action 




GAUGE-COCKS. 67 

of the steam on tlie steel plate, tlie rack will begin to 
revolve round c in direction opposite to the hands of a 
watch. The rack works in a pinion g, and consequently 
the index, will revolve. Eound this pinion is coiled a 
hair-spring, to bring the index back as the pressure is 
taken off. 

83. Gauge-cocks. 
There are three gauge-cocks fitted to each boiler, for the 
purpose of ascertaining the height of water within it. They 
are placed at different heights, the middle one being on the 
level of the water-surface in the boiler ; and consequently 
the lower one is below that level, and the upper one above 
it. If, then, they be opened in succession, water should 
flow from the lowest, a mixture of water and steam from 
the middle one, and steam ought to rush from the upper 
one. These cocks are sometimes placed so that they can 
be reached by hand, although the level of the water in the 
boiler is out of reach. To effect this, pipes connected with 
the cocks run up inside the boiler to the proper height. 
These cocks are frequently tried ; for the salt and silt from 
the water boils into them, and would soon stop them up. 

84. Boiler Water-gauge. 
The water-gauge serves to make the height of water in 
the boiler visible to the eye. Outside 
the boiler AB, and generally not far 
from the gauge- cocks, is a vertical glass 
tube C D, about 16 inches long. The 
ends of this tube fit into metal tubes A C 
and B D, of which the lower one enters 
the water, and the other the steam; 
hence the height of the water in the tube 
is the same as that in the boiler. For 
convenience sake, it is fitted with a 
stop-cock E at the upper, and F at the 
lower end, to cut off the communication 
with the boilers ; there is also a third cock Gr at the lower 




68 THE BOILER. 

end communicating with the stoke-hole, to clear it, when 
it becomes choked, by forcing steam through it. This 
gauge continues to indicate the height of the water when 
the pressure of the steam is below that of the atmosphere, 
in which case the gauge cocks fail. 

85. Kingston's Valves. 
These valves are fitted to every orifice through the ship's 
bottom in connection with the machinery. They are inval- 
uable. It is simply a conical valve, fitted to the conical 
hole in the ship's bottom, the larger part of the orifice being 
outside : a spindle is attached to this valve, which works 
perfectly tight in a stuf&ng-box^ and the inner end of the 
spindle terminates in a cross handle, by which the valve 
can be pulled in or forced out. If, for instance, the blow-out 




cock A should set fast when open, we have simply to pull 
the handle B of the valve C, and the orifice becomes closed, 
and the water is prevented from passing out of the boiler. 
These valves are equally valuable to the sea injection- 
orifice ; for if the sea injection-cock should leak, there is 
then no necessity for docking the vessel to repair, as was 
formerly done. We have but to close the valve, and the 
sea-cock can be taken out and reground. 

86. Wash-plates, or Dash-'plates. 
In the old rectangular flue-boilers, plates so called were 
used to prevent the send of the water when the vessel 



DAMPERS. ' 69 

rolled or lurched heavily ; they were placed in a fore-^nd- 
aft direction, and secured to the upper part of the flues and 
the shell of the boiler, a space being left under them to 
allow the water to maintain its level. They might, per- 
haps, be usefully applied to our screw-ships, which are 
frequently sailing and steaming at the same time. When 
a ship lurches, and the water leaves the weather-side of 
the boiler, there is risk of injuring the crowns of the fire- 
places or upper tubes. 

87. Dampers. 
In most of our steamers there is a damper fitted across 
the funnel, and in some instances worked on deck. It is 
merely a disc, or two half-discs, as the case may be, at- 
tached to a spindle, to which is fitted a handle ; and by this 
the damper is placed horizontally across the funnel, thus 
obstructing the upward current ; or vertically, so as to 
allow a free passage. If the construction and use of the 
throttle- valve are understood, the damper presents no dif- 
ficulty, for it answers the same purpose in the funnel as 
the throttle valve does in the steam-pipe. The damper is 
of great use when the engines are not in motion, and the 
fires are banked up ; and also when the vessel is steaming 
head to wind and sea ; and, indeed, in every instance where 
the draught should be checked, and much steam is not 
required. 

88. The Reverse-valve, 
Although, generally speaking, the pressure of the steam 
is greater than that of the atmosphere, and therefore what 
we usually have to guard against is, the effect of a bursting 
pressure; yet, under certain circumstances, the contrary 
effects may take place, unless a remedy be provided. For 
instance, after the engines have done their work, and the 
fires have been drawn, the outside of the boiler will cool 
down by radiation and contact with the atmosphere of the , 
engine-room, and consequently the steam within the boilers 



70 THE BOILER. 

will rapidly condense and lose its pressure. Or, again, if 
tlie"^res be not properly kept up, the engines will use the 
steam more freely than it is generated. Now either of 
these cases, unless proper precautions were taken, would be 
a source of danger to the boilers ; for if the pressure of the 
external air become much greater than the internal steam- 
pressure, this force may make ' the boilers collapse. This 
is prevented by the use of a valve to each boiler, commonly 
called the reverse-valve, which is opened by the pressure 
of the atmosphere before the crisis arrives, and supplies 
the place of the steam with air. 

Other names are sometimes given to the reverse-valve, 
such as internal safety-valve, vacuu.m-valve, or atmospheric 
valve. 

This valve is commonly made of the same form as the 
safety-valve, but it opens inwards, instead of outwards. It 
requires, however, to be kept in its place by some means. 
If a weight be used, the weight must be connected to one 
end of a lever of the first order, the valve being attached 
to the other end ; and it must be so regulated that the 
atmosphere may open the valve when the steam has di- 
minished to a certain pressure previously fixed on. Gen- 
erally speaking, however, it is kept up in its place by 
means of a spring. 

It is more convenient to place it in 
front of the boiler, and not on the 
top. Here it will be less exposed to 
injury, and less likely to be choked 
up with dirt, and thus rendered 
useless. 

The following kind of reverse- 
valve is very frequently adopted in 
our steam-vessels, and has the ad- 
vantage of not being likely to be af- 
fected by any thing lying or falling 
upon it, because it opens upwards, 
instead of downwards. A is the valve attached to the 




STOP-VALVE. 71 

spindle A B, wliicli works in guides ; tlie valve fits down 
on tlie seat by its own weight ; D C communicates witli tlie 
boiler at 0. Now when the pressure of the air is greater 
than that of the steam in the boiler, it will have a tendency, 
by acting on the under-surface of the valve, to open it, and 
so enter the boiler, thus preventing too great exhaustion. 
Keverse-valves are not needed for high-pressure boilers, on 
account of their great strength. 

89. Communication or Stop Valve. 
In some boilers there is a free passage for the steam to 
pass at all times from the boiler into the steam-pipe ; but 
connected with most boilers of the present day there is a 
valve, called the communication-valve, or stop-valve, which 
can be screwed down or raised at the will of the engineer. 
This valve is very useful ; for it enables the engineer to 
isolate any boiler from the rest, whenever it becomes con- 
venient or important to do so. For instance, in large ves- 
sels, having several boilers, all of them are only used on 
emergencies ; and were it not for the communication-valve, 
the steam from the others would find its way into the empty 
one, and there condense, causing great loss. Again, it is 
of especial service when the fires are banked up. It is 
usual at these times to keep them in such a state of com- 
bustion that the steam may be got up quickly, if requisite. 
To that end the steam is kept at, or rather above, the at- 
mospheric pressure. Now if no communication- valve were 
fitted, the steam, as it is evolved from the water, would 
pass into the steam-pipe, from thence to the jacket, and 
ultimately become jacket-water ; so that every hour the 
water in the boilers would become salter, because that 
which is holding the salt in solution is passing ofi' as steam, 
and leaving the earthy particles behind. Hence it becomes 
necessary to displace a portion occasionally, and pump in 
more. But this would not be the case if the communica- 
tion-valve were fitted, and kept shut ; the steam, as fast as 
it is generated, would be retained within the boiler; a 



72 THE BOILER. 

portion would be condensed by tbe cooling effect of the 
atmospbere on tbe sbell of tbe boiler, but it would mix 
witb tbe water again ; and consequently, bowever long 
tbe fires were banked up, every tbing would remain 
in tbe same state. Tbe engine-room also is kept cool 
by tbis plan, because tbe beat is confined to tbe boiler 
alone. 

War-steamers are now always fitted witb tbese valves ; 
for if tbe steam-pipe were knocked away, or perforated by 
sbot, tbe steam would tbus be prevented from issuing into 
tbe engine-room ; and tbe engineers migbt endeavor, witb- 
out impediment, to repair tbe damage. 

In tbe accompanying diagram, B D C is tbe steam-pipe, 
of wbicb B communicates witb 
tbe boiler, and C leads towards 
tbe engines. A is tbe stop or 
communication valve, wbicb can 
be screwed up or down by turn- 
ing tbe bandle F. Wben open, 
as in tbe figure, tbere is a free 
passage for tbe steam ; but wben 
screwed down on tbe seat D E, 
tbe communication is interrupted. 
If tbe boilers bave a tendency to 
prime, it is as well on first starting tbe engines, to open 
tbe communication- valve only partially at first, to keep 
back tbe water. It serves as a sort of dasb-plate. 

90. Blow-out Cochs. 
Blow-out cocks are fitted to all marine boilers ; tbey are 
for tbe purpose of enabling tbe engineer to cbange tb-e 
water in tbe boiler as it becomes saturated witb salt. A 
pipe is fitted to tbe hottom of tbe boiler, and is continued 
to some convenient part of tbe stoke-bole, from wbence it 
proceeds to tbe outside of tbe sbip. In tbat part of tbe 
pipe wbere it communicates witb tbe stoke-bole tbere is a 
simple stop-cock ; and a portable box-spanner fits tbis cock 




BRINE-PUMPS, ETC. 73 

for the purpose of opening or shutting the orifice. Gener- 
ally speaking, this spanner can only be talcen off when the 
cock is closed : this is to guard against the possibility of 
accidents. 

91. Brine-pumjps, Brine-valves, and Refrigerators. 

The boilers of marine engines are mostly supplied with 
salt water. Now as the water evaporates, and is converted 
into steam, the solid matter is left behind; and after a 
time, when the water becomes fully saturated, and can con- 
tain no more salt in solution, a deposit begins to take place 
within the boiler, which indurates as it is precipitated, and 
forms a ?2ow-conducting substance between the metal of the 
boiler and the water in it.* The evil of this is of two kinds. 
Loss of fuel takes place, because the heat is not able to 
penetrate so freely to the water ; and secondly, the heat, 
not being spread throughout the mass, acts on the material 
of the boiler itself, by which means it becomes rapidly de- 
teriorated. To remedy these evils, it is commonly the 
practice to " blow out" a certain portion of the water at 
stated periods, the place of the supersalted water (or brine) 
being supplied with an extra quantity introduced by means 
of the feed-pumps. 

This process involves a trifling waste of fuel ; for the 
water blown out is discharged into the sea at a temperature 
above 212°, while its place is supplied with water at a tem- 
perature not usually exceeding 100°. 

To obviate these disadvantages, Messrs. Maudslay and 
Field have fitted brine-pumps to their boilers, which are 
worked by the engine ; so that a small portion of' brine is 
drawn off at every stroke. They are so adjusted, with ref- 

* Dr. Davy experimented on various specimens of incrustation, 
and found that, "without any exception, they were composed chiefly 
of sulphate of lime; so much so, indeed, that unless chemically 
viewed, the other ingredients may be held to be of little moment, 
and rarely amounting to 5 per cent, on the whole." — Trans. Br. 
Ass. 1850. 



74 THE BOILER. 

erence to tlie size of tlie feed-pumps, that the quantity tliey 
draw off, together with the quantity of water evaporated, 
shall be equal to that supplied by the feed-pumps * The 
saltness of the water is therefore by these means preserved 
?it a uniform standard, and the danger of injurious deposits 
is prevented. 

Another contrivance, by the same makers, is called a 
refrigerator, by which it is proposed to obviate almost en- 
tirely the waste occasioned by expelling the brine. 

The water supplied from the feed-pumps is made to pass 
through a series of small tubes inside a closed vessel, 
through which the heated brine passes ; and by these means 
the brine gives out its superfluous heat in raising the tem- 
perature of the feed-water previously to its discharging 
itself into the sea. 

92. Surface Blow-out Pipe. 
The water in the boiler is changed from the surface, ana 
not from the bottom of the boiler, as "formerly ; for when 
tubular boilers were adopted, it was discovered that the 



* If the brine drawn off be supposed to contain m times as ranch 
salt as the sea-water, the brine-pumps must extract — th part as 
much as the feed-pump supply. 

For let the sea-water contain — - part of salt; 

. • . the brine contains — parts of salt;' 

and let x = quantity of water supplied by the feed-pump ; 

y = quantity of water extracted by the brine-pumps : 

— = quantity of salt injected into the boiler ; 

and -~ = quantity of brine extracted ; 

and if these be equal, —-==-— 
32 32 

1 
or y = — X. 



BRINE VALVE. 75 

tubes became mucli more rapidly incrusted tban other parts 
of the boiler. A pipe with a stop -cock is fitted to each 
boiler, passing in half way between the upper tubes and the 
surface, the other end being connected with the blow-out 
pipe, or otherwise passing overboard, by which means a 
continuous change of water is going on. The cock is regu- 
lated by hand, and varied according to the circumstances 
under which the boiler is generating steam. 

93. Seaward^s Brine-valve. 
This is an apparatus for allowing the escape of the brine 
from the boiler at every stroke of the feed-pump. It con- 
sists of two valves fixed on the same vertical spindle ; the 
one valve is in the passage between the feed-pump and the 
boiler, and the other to the brine-discharge ; the feed -water 
acts on the under surface of the upper valve, by which 
means it is raised, and allows the feed- water to enter the 
boiler. But in rising it raises also the lower valve, because 
they are connected together by the spindle, and thus the 
brine is permitted to escape ; on the up-stroke of the feed- 
pump the feed- water ceases to flow, and the entrance of 
water and exit of brine stop at the same time. A difference 
in the areas of the valve regulates the proportion between 
the quantity admitted and that expelled. 

94. Brine and Feed Valves, as fitted at the Factory, Ports- 
mouth Dockyard. 
A B (diagram, p. 76) is the brine-valve box, separated 
into two compartments by the partition C D ; and into two 
other compartments by the horiz mtal partition E F, thus 
dividing it into four chambers ; Gr H are two orifices forming 
the seatings of the two valves represented in the figure. K 
is a pipe leading to the boiler, and L is another pipe com- 
ing from the water-space of the boiler, and serving as a 
passage for the exit of water. The valves are connected 
by spindles with the lever M N, and a spring acting on 



76 



THE bo:ler. 



the lever keeps botli valves in their places. P is the feed- 
pipe, and Q that for brine. Kow, when the feed-pump 
forces water through P, it opens the valve G, and enters 




the boiler by means of the passage at K ; and as the valve 
opens, the orifice at H is opened likewise, and the brine 
will issue from L through the pipe Q. The feed- valve Gr 
is four times the size of the brine-valve. 



GHAPTER III. 



THE ENGINE. 



95. Definition. — The Steam-Engine is a Machm in which 
Steam is the only or principal Agent, and Heat the Moving 
Power. 

To illustrate the employment of elastic fluids to drive 
machinery, let us imagine a very large hollow vessel, called 
a cylinder, in which a thick circular plate of metal fits so 
closely as to prevent the passage of the air or other fluid 
between its edges and the surface of the cylinder. Now 
the pressure of the air will be equal on its two sides, and 
the piston, as it is called, will remain stationary ; but we 
may make it move by any one of the three following 
methods : 

1. We may reduce the pressure of the atmosphere on the 
one side, and allow the other to remain unaltered. 

2. We may increase it considerably on the one side, and 
allow the other to remain unaltered. 

3. We may increase it on the one side, and diminish it 
on the other. 

And in each one of these instances the motion of the 
piston will ensue. 

96. Instances of the employment of these several Methods in 

Engines and Machines. 
The first method was applied on what were called at- 
mospheric railways. Steam-engines were employed at in- 
tervals of a few miles to pump out the air from a long hori- 
zontal tube. In this tube was a solid piston connected 
with the railway carriages, which were placed above the 

77 . 



78 THE ENGIXE. 

tube ; and consequently, when the equilibrium was suffi- 
ciently disturbed by the reduction of the atmospheric pres- 
sure on the one side, the unreduced pressure on the other 
side tended to urge the piston, and with it the train of car- 
riages, etc., onwards. This method of propulsion was never 
generally adopted : the many practical difficulties, and a 
great loss of power beyond what was expected by its pro- 
jectors, arising from the development of latent heat, have 
compelled the companies that adopted it to return to the 
usual methods. 

2d. A gun is the most familiar instance of the applica- 
tion of the second principle. The ignition of the powder 
produces a gas of great elastic power, which drives the shot 
against the pressure of the atmosphere. The air-gun also 
acts on the same principle. 

3d. The third principle is but a modification of the two 
former. 

Steam being an elastic fluid, similar in most respects to 
air, is used in one of these three ways, either with or with- 
out the assistance of the atmosphere. 

97. Engines in u^e before the time of Watt. 
The engines employed were those commonly called at- 
mospheric engines. They were used chiefly in pumping 
water from mines. 

98. Newcomen^s Engine. 
Gr (diagram, p. 79) is the upper part of a boiler, which 
serves as a reservoir for the steam, the supply being kept 
up by the ebullition of the water in the lower part of the 
boiler. In this engine the steam has a pressure not much 
greater than that of the atmosphere. The hollow cylinder 
D F is placed directly over the boiler, and is connected with 
it by a pipe, as shown in the diagram. The communica- 
tion can be stopped at will by means of a stop-cock F. D 
E is a movable piston, fitting steam-tight in the hollow cyl- 



NEWCOMEN. 



79 



inder, the upper end of which is open to the pressure of the 
atmosphere (a leading feature in all atmospheric engines). 




A B is a sway-beam, movable about a fixed centre C ; each 
end of the beam terminating in a circular arc. To the 
upper ends of the arcs chains are attached, the one chain 
being fastened to the piston-rod H K, and the other to the 
rod L M for working the pumps. N O is a pipe leading 
from a reservoir of cold water, the supply of which to the 
cylinder is regulated by the cock 0. A smaller pipe also 
leads from the same cistern to the upper part of the piston, 
and was useful at that stage of steam invention for keeping 
the piston steam-tight. (In the present day the correct- 
ness of workmanship would obviate the necessity of this 

second pipe.) There is another pipe E T from the lower 
6 



80 THE ENGINE. 

part of the cylinder, liaving its lower extremity in a reser- 
voir of cold water ; it lias a valve at the bottom, which 
opens outward, and when closed will not allow the water of 
the reservoir to ascend. One point more requires especial 
notice. The pressure of the atmosphere on the upper sur- 
face of the piston is about 14*75 lbs. per square inch. Now, 
whatever be the pressure the atmosphere exerts on the 
whole of the piston, the weight of the pump-rods, etc., must 
be half that amount. Thus, if the pressure of the atmos- 
phere on the upper surface be 2000 lbs., the weight of the 
pump-rods, etc., must be 1000. 

Let us now proceed to describe the action of the engine. 
Suppose it to be arranged as in the preceding diagram, 
with the cock closed, and the whole of the cylinder oc- 
cupied with steam ; then, since the elastic pressure of the 
steam is nearly the same as that of the air, the pressure on 
the two sides of the piston will be equal, and consequently 
the weight of the pump-rods, etc., will preponderate, and 
the piston would ascend, and be pulled completely out of 
the cylinder ; but when in the position represented in the 
figure, we will suppose the cocks F and O to be turned. 
The • steam will no longer enter, and that already in the 
cylinder will be condensed by a jet of water from N ; a 
partial vacuum will be produced ; and if this vacuum were 
perfect, since the pressure of the air on D E = twice the 
weight of the pump-rods, etc., the piston will begin to de- 
scend with the same moving force that it ascended before. 
Again, when at its lowest point, the cock O is closed and 
F is opened ; fresh steam enters, and the piston reascends. 
The water used in condensation, and the condensed steam, 
will run out of the pipe K T into the 'cistern T; and when 
a vacuum is produced in the cylinder, the valve at T will 
prevent the ascent of the water. This is an outline of the 
engine principally in use before the time of Watt ; but 
even then the cocks O and F were worked by the engine 
itself, and not by hand, as the diagram would lead us to 
suppose. It is not intended in this description to give any 



WATT S IMPKOVEMEXTS. 



81 



detailed account of the engine, and for the generality of 
students such a description of an engine now obsolete 
would be useless ; but the foregoing will perhaps serve as 
a basis to further instruction. 

99. The Discoveries of Watt. 
The engine had not advanced beyond this point till the 
time of Watt, when his attention was called to the subject 
from having to repair a model for the lecture-room of Glas- 
gow University. He tried various methods; and for a 
time it seemed impossible to propose aay improvement, 
because the learner will see that it is necessary the cylinder 
should be hot at one time and cool at another for the effic- 
ient working of the engine. At length he conceived it 
possible to have two distinct chambers, the one being the 
steam-cylinder, which should always be kept hot, and, con- 
nected with this, another called " the condenser," into which 
after the steam had done its duty, it should make its exit 
and there be condensed by a jet of cold water continually 
entering from a reservoir. The two conditions may there- 
fore be fulfilled at the same time ; for the cylinder may be 
always kept hot, and the condenser kept cold, during the 
whole time the engine is working ; and hence it follows, 
that the steam, instantly it enters the cylinder, will be 
ready to act with effect ; and again, directly the communi- 
cation is opened to the condenser, it will make its escape ; 
and by its condensation a partial vacuum will be kept up in 
the condenser. But now another difficulty arises ; it is 
evident the water would soon fill up the condenser unless 
removed as fast as it entered ; and besides this, the gaseous 
matter evolved from the water in boiling, not being capable 
of condensation, would destroy the vacuum. To provide 
against this, there must be a pump in connection with the 
condenser, and worked by the sway-beam, to carry off the 
water and air as fast as they enter. A (diagram, p. 82) is 
the passage connecting the cylinder with the condensini^ 
chamber B ; D is the air-pump ; E F is the bucket'worked 



82 THE EXGIXE. 

by the rod G, wliicli is attached to the swaj-beam of the 




engine ; C and K are valves moving on spindles at their 
upper edge, and opening towards the right. In the bucket 
of the pump are two valves, commonly called butterfly- 
valves, E and F, their motion being somewhat similar to 
that of the butterfly's wings. The lower valve C is called 
l\iQ foot-valve, and the upper one K is named the delivery- 
valve. The injection-pipe opens into the condenser as in 
the figure ; and a jet of cold water is continually playing 
while the engine is at work. In land engines the whole 
of this apparatus is usually underground, and surrounded 
by a well of cold water, such as L L in the figure, from 
which the condenser is supplied. The water of condensa- 
tion coming fi'om the air-pump is discharged into a vessel 
H, called the hot-well. From this reservoir the boiler is 
again supplied; and this is a great additional source of 
economy in the engine, for the water thus returned to the 
boiler is warm, and therefore sooner boiled than cold water 
would be. 

100. Principle of the Single-acting Engine. 
Watt conceived the idea tliat it might be possible, after 



SINGLE-ACTING ENGINE. 



83 



the steam had forced the piston downwards to the end of 
the cylinder, to allow it a free access to the under side ; 
when, an equilibrium being thus established, the counterbal- 
ancing weight will draw the piston up ; and when it has 
arrived at the top, a communication being opened with the 
condenser, the steam will be condensed, and fresh steam 
coming in above will perform similar functions. To ac • 
complish this, the cylinder must be closed at both ends. 
The steam must act to force the piston downwards, and 
not upwards, as in the atmospheric engine. A peculiar 
system of valves becomes necessary to effect the several 
operations. 

101. Explanation of the Single-acting Engine. 
Referring to the diagram, p. 84, we will first premise 
that the lower parts of the engine, consisting of the con- 
denser, air-pump, hot-well, etc., are the same as those 
already described, page 82, and therefore a repetition will 
be unnecessary. The pipe H serves to convey the steam 
into the condenser, of which the top is represented in the 
figure. To explain the mode of ingress and egress for 
steam to the cylinder, let Gr Gr be the cylinder, closed at 
both ends, as in the figure, the cover on the upper end 
being made to take oft* for repairs, etc., as occasion re- 
quires; R is a piston-rod moving air and steam tight 
through an orifice in the centre of the cylinder-cover ; E is 
the piston ; S is the steam-pipe ; A, B, and C are three 
valves connected to spindles, and worked by machinery 
outside the engine, which it is not worth our while to ex- 
plain here. But we must notice that B is always closed 
when A and C are open, and viceversd. A rod outside the 
engine, however, connected with the valves, retains A and 
C open, and B closed, till the piston has nearly reached 
the bottom of the stroke; and then, during nearly the 
whole of the up-stroke of the piston, this rod takes the 
position it ought to have if the valves A and C were to fit 
down on their seats, and consequently the valve B opened. 



84 



THE ENGINE. 



'Now, in the first position it may be readily seen that the 
steam can pass along the steam-pipe S to the top of the 
piston ; and since C is also open, whatever be the quantity of 






steam below the piston, it will find a ready egress through 
H to the condenser. Again, when the valves are pushed 
down, since B is open, the steam which was above the 
piston, and has forced it down, is at liberty to act either 



DOUBLE-ACTING ENGINE. " 85 

above or below, and on tbat acconnt its effects are neutral- 
ized. The counterbalance at tbe other end of the sway 
beam now comes into operation, and draws up the piston 

102. Double-acting Engine. 
Its principle is easily understood, being more intelligible 
tban the single-acting engine. In this class of engines the 
steam is allowed to act on the upper side of the piston ; 
and having forced it to the bottom, a communication is 
opened with the condenser, into which it escapes. Then 
another supply is admitted below the piston, to force it up, 
which, when it has done its work, escapes also into the con- 
denser. By these means the alternate motion of the piston 
is produced without the counterbalancing weight, which is, 
therefore, dispensed with in these engines. 

103. Alteration in the Moving Parts of the Engine introduced 
hy the use of the Douhle-action principle. 
In engines hitherto described, since the power is exerted 
downwards at each end of the sway-beam alternately, it 
sufficed to have the piston and pump rods attached by 
chains to the ends of circular arcs, whose centre was the 
middle point of the sway-beam .(see diagram, p. 79); but 
in the double-acting engine the cylinder-end of the sway- 
beam is to be first forced downwards by the steam, and 
then upwards, and consequently the connections must be 
rigid; and hence arises a difficulty, for the piston-rod moves 
in a vertical line, and must necessarily do so, because it 
passes through a steam-tight opening in the cylinder. But 
the end of the sway-beam describes a portion of a circle. 
It is, therefore, very evident that if the top of the piston- 
rod were in direct connection with the extremity of the 
sway-beam, the machinery would be strained. Hence a 
modification becomes necessary. This was also invented 
by Watt, and called the "parallel motion," because a parallel- 
ogram is always the most prominent feature in its outline. 
For a description of the parallel motion, see p. 96. 



86 ' THE ENGINE. 

104. Non-condensing Engine. 
This engine is mostly on tlie double-acting principle, 
but it has no condenser, air-pump, etc., and the steam is 
allowed to escape into the atmosphere after passing through 
the cylinder. For this purpose an exhaust-pipe conducts 
it to some place where it can be emitted. Since it occupies 
much less room than the condensing engine, and requires 
no water for condensing the steam, this species of engine 
is always used on railways and in some river boats, where 
saving of space is a great object. In locomotive engines 
the exhaust pipe passes into the funnel, and as the steam 
rushes out it serves to create a draught. 

105. The Marine Steam- Engine. 
The marine engine is one whose construction is modified 
so as to enable it to be placed in a steam-vessel, and, by 
working, to propel it through the water. In land engines 
the machinery is not in general limited in the space it 
occupies ; part of it may, if more convenient, be placed 
xmderground — this frequently happens with the condenser 
and air-pump ; the cylinder and sway-beams may be of 
any height, and the beams and rods may be of any con- 
venient length. But it is not so with the marine engine. 
Here the sleepers in the bottom of the vessel determine 
the lowest level of the engine ; and the upper deck in 
most cases limits the height.* Moreover, every foot by 
which the engine can be conveniently shortened or nar- 
rowed is so much gain to the ship, by giving more room 
for the men and ofi&cers, passengers, stores, coals, etc. 

106. Side-lever Marine Engine. 
The side-lever engine is a modification of the sway- 
beam engine on shore. When steam was first used as a 
motive power to propel vessels, this was the only kind of 

*Iii most vessels of recent construction the whole engine is below 
the water-level, and this, of course, determines its height. 



MARINE ENGINE. 87 

engine adopted ; but tliey are not so frequently introduced 
at present, because engine makers are trying all means to 
construct engines occupying less space. 

Plate I. is intended to represent a section of the engine 
of H. M. S. Bee, of 10 horse-power, and is drawn so as to 
present to the eye the exterior and interior at the same 
time. ' All the moving parts outside the cylinder are, how- 
ever, omitted in this figure, and will be given subsequently, 
because it was thought that much complexity would be 
thus avoided. In this figure the half of every part is rep- 
resented; and the student must imagine, while reading 
the description, every separate part to be doubled, so as to 
form a complete engine. Ai Ag represents the interior of 
the steam cylinder. This is surrounded, as in the figure, 
by a hollow space, B B, called the cylinder-jacket.* The 
pipe a conveying the steam from the boiler to the cylinder 
has free access to this jacket, which it keeps continually 
filled with steam, ready to enter the cylinder whenever it 
has an opportunity. In the meantime it becomes useful 
in keeping the cylinder warm, so that no condensation 
takes place within the cylinder. At C is a valve, called the 
expansion- valve, which, during the ordinary working of 
the engine, remains open. We shall refer to it again here- 
after ; but at present we will suppose it Ice'pt open. The 
steam can, therefore, make its escape from the jacket into 
the hollow space D, surrounded by the semicircular casing, 
of which E E E represents the half. If allowed to make 
its way, it would enter both the steam ports F F at the top 
and bottom of the cylinder ; but this must not be per- 
mitted. That the engine may receive the steam at proper 
and regular intervals, a valve, called from its shape " the 
D-slide," is introduced. This valve is represented by itself 

* Jackets are now seldom used, but a coating of felt covered with 
wood is put on instead. Fuel would most probably be saved if the 
jacket were retained, and ccwered over with non-conducting sub- 
stances. 



88 



THE ENGINE. 



1^ 



in tlie adjoining diagram. The flat 
projecting surfaces a b press against 
the projecting faces of the steam- 
ports FF (PI. I.) ; the middle por- 
tion c recedes a little, as also does 
the middle of the semicircular back 
of the slide /.* The slide is hollow, 
and is usually of such a length that 
the faces a b may cover both ports 
FF at the same time.f Suppose, 
now, the valve to be in its place, 
and put in such a position as to cov- 
er both ports ; then the steam from 
the boiler, passing by the pipe, en- 
ters the jacket, and making its way 
through the orifice at C, can sur- 
round the middle part of the slide, 
but can proceed no farther. Let, 
however, a force act on the rod d to 
draw it. up a few inches ; then the 
upper port is opened to the steam, 
and the lower port is uncovered, 
permitting a free communication be- 
tween the portion of the cylinder 
below the piston and the condensing- 
chamber GGG. The steam enter- 
ing by the upper port will conse- 
quently be unopposed in its endeavor 
to force down the piston H H. It 
will therefore descend, and bring 
down the rod 1 1, and whatever part 
of the machinery outside the cylin- 
der may be connected with it. When 



* The space between e e and the interior of the slide-casing is 
packed, to prevent steam from passing up or down. 
t The sUde in the annexed figure is made larger than necessary, to 



give a clearer representation. 



MARINE ENGINE. 89 

the piston lias come to the bottom of the cylinder, let the 
slide-rod be pushed down some inches, till the face h has 
uncovered the lower port to the steam ; that which has en- 
tered above the piston H by the upper port F will be able 
to make its escape, by the same port, over the upper edge 
of the face a down the hollow of the slide into the conden- 
ser Gr ; and at the same time the steam entering by the lower 
port, meeting with no opposition, forces up the piston, to- 
gether with the piston-rod. Hence by moving the slide- 
rod up and down, the reciprocating motion of the piston 
and rod is produced, and with them the parts outside the 
engine to which we wish to communicate motion. The 
vacuum in the condenser is kept up by a jet of cold sea- 
water flowing in by means of a pipe through the ship's 
side, and called the injection-pipe. This supply is regu- 
lated by a cock in it, called the injection-cock, which is 
•worked, by hand. L L is the air-pump: it is similar to 
those in land engines ; it has its bucket M M fitted with 
butterfly-valves NN, which turn on their spindles, and 
allow the water below them to pass above the bucket. K 
is a section of the foot-valve'^ (as it is called), which per- 
mits the passage of water from the condenser to the pump, 
but prevents its return into the condenser on the down- 
stroke of the pump. The valve Q is called the delivery- 
valve. Its office is to take off the load of water from the 
top of the bucket as it descends. is the hot-well; and 
above that, in many engines, is a conical vessel P, open at 
the top, called the air-cone, its only use being to prevent 
any chance of the water in the hot- well escaping into the 
engine-room ; it is not, however, generally fitted now, hav- 
ing been found unnecessary. There are two orifices in the 
hot- well, the diameter of one being nearly six times that 
of the other. The larger one communicates with the sea 
through a pipe, called the waste-water pipe, by means of a 



* The foot-valve, which is usually rectangular, has generally a 
guard at the back ; but this would have confused the diagram. 



90 



THE ENGINE. 



valve called tlie discharge or sluice valve ; the smaller one 
leads to a forcing-pump, by which the boiler is supplied 
with water of about 100° temperature. In the waste- 
water pipe is fitted a valve, close to the ship's side, which 
is called the sluice or discharge valve. 

107. Blow-through Valve. 
The accompanying diagram represents the section of a 
D-slide, with its casing and the steam- 
ports of the cylinder. C is the sec- 
tion of the slide, D E the casing, A 
and B the upper and lower steam- 
ports ; the shaded part at D represents 
the packing at the upper port; and E 
that at the lower port. E F H is the 
part of the casing where the blow- 
valve is fitted, which contains a parti- 
tion E G. This partition has a circu- 
lar orifice, which is closed by the 
valve Gr (when in its seating). Now 
when the orifice is thus closed, tlie 
steam which surrounds the waist of 
the slide cannot pass below the partition E G-. This is the 
state in which it ought to be while the engine is working ; 
but so soon as the valve G is raised by the spindle F, a 
passage is made for it into the condenser through the 
lower part of the casing at H, and thus the steam can enter 
the condenser and expel the air without entering the 
cylinder. 

108. Method adopted, for keeping the Cylinder, Air-pum/py 
Slide-valve, etc., air and steam tight. 

Referring to the middle of the cylinder-cover, where the 
piston-rod passes through it, we see that the orifice is 
shaped in the form of a circular cup, having a deep pro- 
jecting flange ; it is represented by R R, etc., in Plates I. 
and II. This is called the stuffing-hox^ for the following 




STEAM CYLINDER. 91 

reason : the hollow cup is made much larger than the pis- 
ton-rod, and the space between the stuffing-box and piston- 
rod is filled with a gasket of plaited hemp. On the inside 
of the stuffing-box, and below the packing, is a small brass 
bush, fitting tight round the piston-rod, but so as to let it 
move in it. This will prevent any packing from being 
forced down into the cylinder by the piston-rod. Above 
the stuffing-box is the "stuffing-box cover, ^'' or "gland,'''' 
S S S ; it has a projecting flange similar to that of the 
stuffing-box, and the two are connected by bolts and nuts. 
Reference to the figures will show that by screwing down 
the gland of the stuffing-box the packing is forced into 
contact with the piston-rod and stuffing-box at the same 
time, and thus escape of steam is prevented. We ought 
perhaps to notice here, that an engineer must not be satis- 
fied that the packing fits tight ; for unless the whole space 
between the cup and the piston-rod be filled up, steam will 
escape. The upper part of the "" gland" in contact with 
the piston is hollowed out ; it is kept full of melted tallow, 
for lubricating the packing. A similar description applies 
to all those parts where a rod has to work air-tight through 
an orifice, as may be seen in the figure by referring to the 
rod of the air-pump and slide valve. 

109. Details of the Piston of the Steam- cylinder. 
HH is a section of the piston. It will be seen that it 
is hollow, for the sake of lightness, and of considerable 
depth, to prevent the force of the steam at the edges from 
deflecting it. Formerly it was the custom to keep it 
steam tight in the cylinder by hemp-packing, interposed 
in a hollow groove TT at its circumference, between it 
and the cylinder ; but in the present day, metallic rings, 
placed within this groove, surround the piston, and are 
iorced out towards the cylinder by springs or packing. A 
f'at horizontal ring, as shown in the figure, is then bolted 
down to the outer edge of the piston, and keeps the rings 
in their place. The lower surface to the right is cut away, 



I 



92 THE EXGIXE. 

that when the piston is at the- bottom of its stroke, the 
steam entering at the lower port may have free access to 
the under-side of the piston, and force it up again. The 
piston is not allowed to come in contact with the top or 
bottom of the cylinder ; and the space between it and the 
top or bottom, when at the extreme of its stroke, is called 
the clearance. 

The piston-rod is conical at its lower end, and in some 
cases is kept in its place by a key driven through it and 
the central part of the piston. But the usual mode at pres-^ 
ent is to have a thread cut in the rod and a nut to corres- 
pond, by which means the piston is secured more firmly 
to the rod. 

The air-pump bucket is kept tight in its cylinder by 
means of hemp-packing. 

110. Working Parts of side-lever Engines. 
The part U U (Plate II.), going across the cylinder, and 
connected to the piston-rod I, is called the cylinder cross- 
head. The smaller cross-piece v t; is called the air-pump 
cross-head. The rods X X are termed the cylinder side- 
rods ; and y y the air-pump side-rods. Z^Zg, ZjZg, are 
called the sway-beams, or side-levers. Now it will be seen, 
by inspecting the figure, that as the piston-rod moves 
down, the cylinder cross-head U U) the side-rods X X, and 
the ends ZiZ^ of the side-levers, will move down with it. 
But the side-levers move round their middle point p (which 
is called the main centre) ; and therefore as ZiZi descend, 
the ends Z2Z2 will ascend. Again, q q are the paddle- 
shafts, that is to say, the shafts to which the paddles are to 
be attached, and the revolution of these shafts will cause 
the revolution of the paddles. These shafts are in con- 
nection with the parts r r, called the cranks, the farther ex- 
tremities of which are connected together by the crank- 
pin. Also, the upper end of the connecting-rod s embraces 
this pin by means of the connecting-rod brasses 1 1, while 
its lower end passes through the cross-piece g g, to which 



DETAILS OF EXGIXE. 98 

it is rigidly secured. This cross-piece is called by some 
ihQ fork-head, and by others it is termed the cross-tail. Let 
now the ends Z2Z2 of the sway-beams be supposed to move 
np, as before, by the admission of steam into the cylinder 
above the piston. Then the fork-head and connecting-rod, 
being forced up, will cause the cranks r r to rotate ; and 
as they revolve, the shafts q q will revolve with them, and 
produce a revolution of the paddles. This motion will 
continue till the cranks are vertical; and if the engine 
have acquired sufficient momentum, they will pass the 
highest point, and be in a proper position to commence the 
other semi-revolution. We have before shown that the 
upward motion of the crank was produced by the pressure 
acting on the upper side of the piston forcing it down. 
Let us now, in the next place, imagine that the steam has 
been admitted below the piston, which is nearly at the bot- 
tom of the cylinder ; then, on the contrary, the connect- 
ing-rod will be dragged down, and the cranks will descend, 
till they come to their lowest position, causing the paddles 
to perform the other half of their revolution through the 
water. 

We will next proceed to describe the action of the air- 
pump. The reader should have Plates I. and 11. before 
him, and refer to each as occasion requires. First, looking 
at Plate IL, we see that the air-pump rod is connected to 
the air-pump side-rods y yhj means of the cross-head vv ; 
and hence, as the side-levers ascend and descend (vibrating 
round their main centre p), the piston-rod is forced up and 
down again. The air-pump is lined with brass, to give a 
better surface for the packing of the bucket to travel over : 
otherwise the salt water would oxydize the iron, and the 
packing (being of hemp) would soon be worn away. This 
is not necessary in the steam-cylinder, because the steam 
does not act so injuriously on the iron, and the packing is 
usually metallic. Metallic packing has also been tried in 
the air-pump. The action may be more clearly seen by 
referring to Plate I. As the rod of the air-pump is pushed 



94 THE ENGINE. 

up, the valve K, wMcli is called the foot- valve, is raised by 
the pressure of the water under it in the condenser, and 
it by these means fills the body of the pump under the 
bucket. Again, as the rod is forced down, the bucket M M 
coming in contact with the water, the valves N IST will open, 
and admit the water above the bucket. When, then, the 
bucket is raised the next time, the water is lifted with it, 
and, pressing against the under-surface of the delivery-valve 
(as it is called) Q, makes its escape into the hot-well O, 
where it would accumulate, were it not that an escape is 
provided through the ship's side by the waste- water pipe. 
The waste-pipe must be of considerable size, because it 
has to afford a passage, during a very short period of the 
stroke, for all the water that has accumulated in the engine 
during the whole stroke. 

111. Method of worhing the Slide. 
The shaft 11, called the weigh-shaft, is fixed to some 
part of the framework of the engine by plomer-blocks, in 
which it can revolve ; so that when a force acts on the 
stud 2, at the end of the arm 12, to push and pull it alter- 
nately, it will make it move either from left to right or 
from right to left, as the case may be. It will be seen that 
two arms 34, 84, are fixed to the shaft 11, and therefore 
the vibrating motion of the shaft through a small angle 
will be productive of an oscillating motion of these hori- 
zontal levers ; hence the points 83 will alternately rise and 
fall. To these points are attached side-rods 35, 35 ; and 
their upper ends being connected together by the cross- 
liead 55, its middle point supports the slide, by means of 
the end of the slide-rod, at the point 6. It will be observed 
that there is a weight 44 at the end of the levers. The office 
of this weight is to balance the weight of the slide, so as 
to keep the slide in its position when the engine is stopped, 
viz., with both ports closed for steam : or otherwise the 
slide would drop, and thus open the port for steam, nnd 
move the engine. If the slide be thus balanced, the only 



STRAP, GIB, AND CUTTER. 



95 



power requisite to work it will be tliat wMcb. suffices to 
overcome its friction. 

The names of the machinery just described, connected 
with the slide, are as follow : 

The part 11 is called the weigh-shaft. 

The weight 44 is called the back-balance. 

That part of the lever from the weigh-shaft to 33 is 
called the valve-lifter or slide-lever. 

The rod 12 is called the gab-lever or eccentric-lever. 

The cross-piece 55 is called the valve cross-head. 

112. Strap, Gib^ and Gutter. 
This contrivance is used to connect the working parts 
of a steam-engine together, and the advantage of using it 
consists in the facility it gives to the engineer of tighten- 
ing up the parts of the engine that become worn, together 
with the power of taking the engine 
apart when necessary. In the ad- 
joining diagram, a is a bearing 
which is to be connected with the 
rod b, so as to be freely movable. 
The shaded parts of the diagram re- 
present two brasses ; one of which, 
viz., the lower, rests on the end of 
the rod, and the upper one on the 
bearing a, leaving a space between 
them, each brass being hollowed out 
to hold the bearing, c c c is a strap 
surrounding these brasses and the' 
sides of the rod. The rod and the strap have a key -way cut 
through them, into which first of all the piece of iron d d d 
(called the gib) is inserted, and then the cutter or key ee is 
driven in, securing the whole firmly together; and as the 
bearing wears, by driving up the key, the parts are brought 
close together again. To effect this, spaces are purposely 
left in the slot- way. It is the practice with engineers to 
drive all keys towards the main centre of side-lever engines. 




\fO THE ENGINE. 

lis. The Cylinder Escape-valves. 

If we watcli the action of the slide, we perceive that 
all ingress or egress to or from the cylinder is cut off by 
the slide as the piston is coming towards the end of its 
stroke ; and consequently whatever is contained within the 
cylinder must remain there, unless some means of escape 
be provided. Now, from various causes (such as conden- 
sation, priming, etc.), water is apt to collect in the cylin- 
der, both above and below the piston ; and, since it is in- 
compressible, if it accumulate to any considerable extent, 
the engine will either be stopped or some accident will 
happen. Either of these may, however, be prevented by 
providing the cylinder with valves for allowing the water 
to escape ; that for the space above the piston is in the 
cylinder-cover, and is mostly retained in its place by a 
spring : the lower one is exhibited in Plates I. and 11. ; 
the letter Z represents the weight for keeping it in its 
place. The valve and orifice communicating with the 
cylinder are both shown in Plate I., and the outside ap- 
pearance is seen in Plate II. These valves are generally 
loaded with a weight greater than that of the safety-valve, 
otherwise they would open with every fresh introduction 
of steam. 

In engines working at great speed, such as those driving 
the propellers of most of our block-ships, the load on the 
escape-valves is not greater than that on the safety-valve. 
At first starting the engines, it is a common thing to see 
them open, and allow the steam and water to escape ; this 
goes on till the engine is fairly under weigh, when they 
remain closed. The object of this is, that the engine may 
not be overtaxed; and, as is observed in Article 116, 
cocks are fitted to assist the valves, or other means are 
adopted of allowing the water to escape. It is a good plan 
to have a brass or copper case over the upper escape- valve, 
fitted with a nozzel to emit the water clear of the persons 
standing in the engine-room. 



parallei-inoiioa uar. 

The jiccompanying figure represents tlie tliree lines A B, 
B C, CO, whicli form part of the previous figure, but are 
separate! from it, because the rest is not wanted in our 




present 3onsideration of the subject. Now as C moves 
rouud the main centre 0, A B will revolve about A, and 
the rods A B, B C, C will come into some other position 
A B', B'C, CO, the point B' being drawn to the left, and 
the lower point C to the right. Again, when it comes 
into the similar position below CO, the same will take 
place. But if we produce B C both ways, it will cut B'C 
in some point c, which is evidently the point of which we 
were speaking ; for since the whole of the line B C is ver- 
tical when C is horizontal, and since c is in this vertical 
line (produced) at both extremes of the motion, it follows 
that it cannot be out of that vertical line to any sensible 
extent at any period of the motion, and therefore the point 
c describes, approximately, a straight line. It is found by 
a geometrical investigation (given in the Appendix), that 
unless A B' be small, the point c divides B C into two 
parts, which are reciprocally proportional to A B and C ; 
that is to say, B'c : c C : : C'O : A B^ 

Our next object is to insure that the point D (the point 
of connection between the cross-head and cylinder side- 



jjj vui^ ..v.. paic^xici motion" we anabisiaua a set oi 

bars and rods fitted to tlie cylinder side-rods X X, and in- 
tended to keep their upper extremity in a vertical straight 
line, or nearly so, during the whole of the stroke. The 
necessity of some such contrivance is obvious (see Art. 
103) ; for, as we have before observed, the end of the side- 
levers ZiZi describes a circular arc, and this would have 
the effect of alternately thrusting the piston-rod against 
one side or other of the stuffing-box. In Plate 11. we have, 
for simplicity's sake, left out the parallel motion ; but the 
accompanying diagram 
will enable us to suppose | 
those parts that are want- 
ing, and the figure will| 
not become too compli- 
cated. Let DF repre- 
sent the side-rod; F 
half the sway-beam; 0| 
the main centre ; B Gr, B C, 
two rods, connected to 
each other at B, and to the 
side-rod and sway-beam 
at G" and C respectively (and thus forming a parallelogram) ; 
A B another rod, connected with the two former at B, and 
moving round a fixed point A. This series of rods is 
called the parallel motion ; and our object is to determine 
iheiT proper lengths, that they may effectually perform their 
duties. To do this, we shall have to show that there is 
always som0 point c in B C which describes approximately 
a straight line, and then to find the proportionate lengths 
of the various rods, that the path of D (where the piston 
cross-head is attached) and c may be made similar. We 
will first, however, give to these rods the names they gen- 
erally receive : FO being the half sway-beam, and.DF 
the cylinder side-rod; AB is called the radius-bar, or 




y bridle-rod: BC II 



ANNULAR AIR-PUMP BUCKET. 



101 



117. The Foot-valve not absolutely necessary. 
Although most engines are fitted witli a foot-valve, yet 
they may be, and are, contrived so as to do without it. 
But then the steam must not enter the condenser so low 
down as in other engines ; and the air-pump must work 
as near the bottom of the condenser as possible, that the 
bucket may plunge into the water at every stroke, to en- 
able it to extract a portion each time, and prevent the 
engine from becoming choked. Messrs. Napier of Glas- 
gow have constructed some engines to work without foot- 
valves ; but instead of allowing the steam to enter the con- 
denser downthQ slide, they have reversed the operation, 
and exhaust up the slide, and thus into the condenser ; so 
that the water in the condenser may rise to almost any 
height without entering the slide, because the steam-orifice 
is at the top. 



118. The Annular Air-pump Bucket. 
The annular air-pump bucket may be conceived by sup- 
posing a piston from which two annular spaces have been 
taken out, as in the following diagram, of which Fig. 1 is 
the plan, and Fig. 2 at A exhibits the section. The annular 
spaces are connected together by radii, as is shown in Fig. 1. 





Fig.l. 



Fig. 2. 



102 THE ENGINE. 

Over these anniilar spaces circular rings of metal are 
fitted, and these rings are called the valves. The valves 
are shown in section in Fig. 2, at a a and h b. They work 
in guideS; and are only allowed a certain amount ot lift. 

119. Annular Delivery -valves. 
Annular delivery-valves are of the same kind as the 
valves of the air-pump bucket. There is, however, but one 
circular orifice in the seat, and consequently only one an- 
nular valve. It is shown in section in Fig. 2 at B ; c c is 
the valve, and d d the orifice. Maudslay's double-cylinder 
engines are fitted with these. 

120. Peculiarity in the Air-pum]p of a Steam-engine. 
If we look upon the condenser as the well from which 
the water is to be pumped, we notice a manifest difference 
between the duty of the air-pumps and that of other 
pumps, inasmuch as the condenser is not open to the air, 
and the ascent of the water cannot be assisted by the pres- 
sure of the atmosphere. The bucket therefore cannot be 
raised to any great height . above the condenser, with the 
expectation that the water will follow the bucket on its 
up-stroke. 

♦ 
121. Air-'pum/p without a Delivery -valve. 

Instances have occurred in which engines have worked 
for some time after the delivery- valve had given way. 
For example, H.M.S. Yixen, when on the China station, 
broke the spindle of her delivery- valve, and proceeded 
without it ; and scarcely any appreciable difference in the 
working of the engine could be perceived. But it is clear 
she must have been fitted with a foot- valve, and it is also 
evident that the air-pump had more work to do in the up- 
stroke ; and though the mean amount of work is the same 
in an up and down stroke, yet the bucket would be more 
strained ; and, unless it had been in good condition, it 
would not have lasted long when subjected to this trial. 



SLIDE-VALVES. 103 

In quick- working engines, the sliock on the delivery- 
valve on the ascent of the bucket of the air-pump is very 
great, producing great wear and tear and a disagreeable 
noise. To prevent this, a small valve is sometimes fitted 
to admit air above the bucket as it descends ; and lately 
canvas or vulcanized India-rubber delivery-valves have 
been fitted. These work very well ; but the former leak 
when the engine stops, so that it becomes necessary to 
blow through frequently to keep the condenser clear. In 
some engines the delivery- valve is divided into two parts, 
these parts being set at different angles. These valves 
will open at different portions of the stroke, and divide 
the shock between them. Annular delivery-valves are 
less noisy than those that work on spindles. 

122. Douhh-adiny Air-pump. 
For a description of this pump the reader is referred to 
the last article of Chapter TV. 

123. Discharge or Sluice Valve. 
This valve is fitted in the waste (or discharge) water 
pipe, at its junction with the ship's side. In some ships 
there are two valves ; one a common lifting- valve, and the 
other a sluice-valve, which is screwed across the opening 
of the pipe. This valve must of course be opened before 
attempting to start the engine, or otherwise the hot-well 
will burst, or the air-pump break down. The use of this 
sluice-valve is to cut off the communication with the sea 
when the engine is not at work. 

124. Slides fitted to Marine Engines. 
They are called the Long D-Slide, the Short D-Slide, 
the Locomotive Slide, Seaward's Slides, and Cylindrical 
Slides. 

125. Details of the Long D-Slide. 
This slide has been partially described in giving the de- 
tails of the beam-engines ; but there are still some points 



104 



THE ENGINE. 



that require consideration ; for as it is the apparatus by 
whicli the supply and exit of steam are managed, all its 
peculiarities deserve attention. With this slide, the steam, 
after entering the lower port, and doing its work, com- 
monly makes its exit through the same aperture (by rais- 
ing the slide) direct into the condenser ; while that which 
enters the upper port has to make its way down the hollow 
of the slide before it can reach the condenser. This, how- 
ever, is not always the arrangement ; for, as we have said, 
in some engines of Napier's construction the steam from 
the upper port rushes at once into the condenser, while 
that from the lower port has to make its way up the slide 
into the condenser. 

Slides are at times hard to move, because of the vacuum 
in the cylinder when the engine has stopped. In such 
case the grease-cock of the cylinder should be opened and 
the air admitted, which will get over the difficulty. 




126. Short D-Slide. 

The Long D is made with a 
passage entirely through it, and 
has but one exhaust passage ; but 
the short D has two separate ex- 
haust or eduction passages, fitted 
to allow the steam to pass to the 
condenser, one at the top of the 
slide-case, and the other at the 
bottom. 

The accompanying diagram rep- 
resents the Short D-slide. A and 
B are the upper and lower slide- 
faces, and C D is the rod by which 
they are both worked. At the 
back of each slide-face may be 
seen a flat partition to separate 
the steam from the exhaust side of 
the slide. 



ECCENTRIC STOPS. 115 

had originally, the eccentric would fall into gear, and the 
shaft and eccentric-pulley would again commence revolv- 
ing round q^ as before. But, instead of this, let us suppose 
the starting-bar to be moved to the opposite direction, so 
as to let the steam act on the other side of the piston, the 
point a will then descend instead of ascending ; and we 
will suppose further, that in this direction the shaft can 
revolve freely without moving the eccentric pulley and 
rod. Let the engine be moved thus till the point a comes 
to d, that is, till it is in the middle of its path, but on the 
opposite side of the vertical. Now since the eccentric- 
pulley has not been moved, and the piston is in the middle 
of its stroke, the whole engine is in precisely the same cir- 
cumstances it was at first, except that q^ a and a h occupy 
the position qd, dh. Let the eccentric be now thrown into 
gear, and we shall find as the steam acts on the piston, and 
forces up the point h in the direction of the arrow, the 
crank d q will move from left to right : and causing the 
paddles to revolve in this same direction, the vessel will 
gather sternway. It is clear, therefore, that the shaft must 
be free to rotate backwards within the eccentric-pulley 
during half a revolution of the engine, to enable the engine 
to be put in the second position while working it by hand ; 
and afterwards the engine, as soon as the eccentric is thrown 
into gear, must of itself act upon it. This is accomplished 
thus: On the shaft A is placed a 
stop cd] and on the eccentric B is 
cast another stop a h. Then, as the 
shaft revolves from right to left, the 
point a comes into contact with c, and 
so the eccentric and shaft revolve to- 
gether so long as the motion con- 
tinues in the same direction ; but so 
soon as the engine is reversed, these stops become detached ; 
and after passing through the position they occupy in the 
diagram, the face h comes (after half a revolution) into con- 




116 THE ENGINE. 

tact with d, and tlie engine is in tlie position to work the 
reverse way. 

139. To find the Travd of the Siide from the Throw of the 
Eccentric and vice versa. 
If the length of the gab-lever 12 (in Plate II.) be equal 
to that of the valve-lifter 13; the travel of the slide will be 
double the throw of the eccentric ; but this is oftentimes 
not the case : still, however, the one may be approximately 
found from the other by a very simple proportion ; for let 
a 6 be the gab-lever and c I the valve-lifter, each of them 
being supposed at the extreme of its stroke ; then suppose 
the point a to come to e and do d, e and d being the other 
extreme positions of the levers; 
therefore a e is the throw of the ec- 
centric, and c d the travel of the slide. 
Now ah e and chd are two similar 
triangles ; therefore ae\ ah: \d'c\ch\ 
or, in other words, twice the throw of 
the eccentric i length of gab-lever : : 
travel of slide : valve-lifter. 

140. The Douhh Eccentric, or Link Motion. 
In a locomotive engine it is usual to have two eccentrics 
keyed to the shaft, to produce the head and back motion. 
This is sometimes called Stephenson's link motion, and it 
is being very commonly introduced into our steam navy, 
particularly for engines to turn the screw-propeller, be- 
cause a sudden reversing action is more desirable than with 
paddle propulsion.* The accompanying figure represents 
the double eccentric. There are no stops on the shaft as 
in the common single eccentric, but they are keyed to it, 
and all back-lash is therefore prevented. A and C are the 

* The use of these eccentrics is not Hmited to engines for driving 
the screw ; the Sampson and Bulldog have engines fitted with them, 
and these are paddle-wheel vessels. 




THE THROTTLE- VALVE. 117 

two eccentrics, and B is the shaft ; D E is the arc of a circle 
connecting the ends D and E of the eccentric-rods A D and 
C E ; F is the gab-lever pin, which travels in the slot- way 
D E. By means of suitable machinery, worked by hand, 
the arc D E may be raised or lowered so as to cause the 
pin F to traverse the space from D to E. There are joints 
at the ends of the rods at D and E, and B is the centre of 




3^ 



the circular arc D E ; therefore F can traverse the slot-way 
freely. Now when F is at D, the eccentric A D works the 
slides horizontally, and when it is at E the eccentric C E 
works it. And one is set for producing the motion for 
head- way, and the other for stern- way. Lastly, when F is 
half-way between D and E, the slide" will be stationary. 
When fitted with the double eccentric, the engines cannot 
be worked by hand. 

141. The Throttle-valve. 
This valve is for the purpose of regulating the supply 
of steam to the cylinder, and is worked by hand in marine 
engines. In land engines it is usually regulated by the 
governor. In some engines it is fitted in the steam-pipe, 
not far from the cylinder, and in others in a port-way be- 
tween the jacket and slide-casing. This valve is circular 
when fitted in the steam-pipe, and rectangular when fitted 



118 THE ENGINE. 

In the port-way. Where no expansion-valve is fitted, it ia 
used to economize fuel ; but its general value is, that it 
enables the engines to proceed more slowly when orders 
are given to ease them, or on first getting under weigh, 
that the steam may be admitted gradually ; as also when 
they would use more steam than the boiler can readily 
supply. ' ^ 

/ 142. The Expansion-valve. 

The expansion- valve is for the purpose of cutting 'off the 
steam from the cylinder at various portions of the stroke 
of the piston, in order to economize fuel. The principle 
by which this is accomplished will become apparent from 
the accompanying figure. Let A D represent the steam- 
pressure at the commencement of the stroke of the engine, 

which is represented 
by A B ; and suppose 
the steam to act with 
uniform force through- 
out the space A C, sup- 
posed to be an exact 
fractional part of A B ; 
make CF, FG, etc., 
each equal to A C. 
Through the points C 
F G, etc., draw C E, F L, G M, etc., perpendicular to A B. 
Make CE = AD, FL = iAD, GM = JAD, and soon. 
Join D E, and through E, L, M, IST, etc., draw a free curve. 
Then since, by the law of the elastic pressure of a gas, the 
pressure diminishes as the space it occupies is increased, it 
will follow that, if a perpendicular be drawn from any point 
of A B to meet the upper curve, the part intercepted by 
these two lines will represent the pressure of the steam at 
the corresponding portion of the stroke ; for at F, where 
the space A F = twice A C, L F has been made equal to 
half A D. Again, at G, where the space A G is three times 
A C, we have G M = one-third of A D, and so on : the per- 




EXPANSION. 119 

pendiculars, therefore, at all these points being inversely 
as the corresponding spaces, it will be the case also at all in- 
termediate points, and consequently generally true through- 
out the curve. Pei'pendiculars, therefore, from all points 
from A to C, will represent the pressure of the steam before 
its expansion ; and those drawn between C and B, and in- 
tersected by the curve, will represent the pressures after 
expansion. The sum of all such lines, therefore, will rep- 
resent the whole sum of the pressures during the stroke. 
These we may suppose the same in amount as the sum of 
a series of lines intercepted between the upper dotted line 
and A B. 

Hence the mean pressure during the stroke will be rep- 
resented by some line Q'B. 

But, since at the end of the stroke the pressure of the 
steam is QB, it follows (the whole cylinder being filled 
with steam of that pressure) that the quantity of steam used 
in one stroke may be represented by Q B ; we arrive, there- 
fore, at, the following result, viz., that steam whose quantity 
is represented by the line Q B has been enabled, by giving 
so great an initial force, to perform work whose mean effect 
is Q'B. Hence the evident advantage of working expan- 
sively ; that is, of letting in the steam at first at a high 
pressure, and cutting it off at an early period of the stroke. 
Lastly, the higher the pressure at first, and the earlier the 
period at which the expansion commences, the greater the 
advantage; the only limit being, that the final pressure, 
must never be less than the resistances caused by the engine 
itself, such as the friction, labor in working the air-pump, 
etc. ; and the initial pressure must not be greater than that 
which the safety of the boiler and strength of the machinery 
would warrant.* 

* If, when the space traversed by the piston =:w times AO, we 
call the space x and the perpendicular y, we shall have 

a; = wAC, andy = -EC 
n 

.'*. multiply these together, we have 

a;y=:AC.CE " 



120 



THE ENGINE. 



143. Exjpansion-valves. 

The valve used is generally of tlie Cornisli double-beat 
description; it is sometimes, however, the throttle- valve 
or the gridiron-valve. The latter is fitted to most of the 
Scotch engines. ' 

144. ITornhlower's Valve. 

When the practice became general of working engines 
at a higher pressure, it was found necessary to introduce 
this valve. Let us suppose, for the sake of illustration, the 
pressure on one side of a valve to be 
greater than that on the other by 20 lbs. 
per inch, and that the valve has an area of 
50 inches; then the valve will be held 
down by a force of 1000 lbs., and will re- 
main fixed, unless a power greater than 
1000 lbs. be applied to it; and in conse- 
quence the valve will not only be raised 
with difficulty, but the power required 
will soon cause it to loosen and detach it- 
self from its rod. To remedy this, Horn- 
blower conceived the idea of having a 
valve similar to the common valve, only 
fixed ; and a portion of a pipe was made 
to slide within another portion, like the 
tubes of a telescope, so as to fit down on 
this valve, and prevent the progress of the 
steam, or to rise up and allow it a passage. 
The resisting pressure being now only 
exerted on the edge of the tube, does not produce the same 
injurious effects as it did before. The accompanying figure 
will explain it more clearly. A B C D E F is the steam- 
pipe, G the fixed valve, H K a section of the sliding tube. 
In the present position the steam can pass between the 




which is the equation to a hyperbola whose asymptotes are A B and 
A D. The curve E M N Q is therefore a hyperbola. 



CORNISH VALVE. 



121 



valve G and tlie lower rim of the tube K ; but if the two 
are brought into contact, the passage is obstructed, and the 
progress of the steam below G is prevented. This may be 
considered as the first origin of the Cornish double-beat 
valve. 

145. The Cornish Double-heat Valve, 
The principle on which this valve is constructed can be 
readily understood after a personal inspection ; but, like 
many other pieces of machinery, there is great difficulty 
in representing it clearly to those who are not accustomed 
to inspect drawings. Im- 
agine, however, A B to be 
the section of a solid circu- 
lar plate of metal supported 
by the cylindrical surface 
A B C D, in which cylindri- 
cal surface are narrow ver- 
tical apertures, as repre- 
sented in the figure, for the 
purpose of allowing the pas- 
sage of steam ; F G is a 
section of a casing which 
surrounds all this. This 
casing is open at the top, 
and is connected with the . 

rod H K by radii, which allow steam to pass between 
them. When this casing is pushed down, the annular 
apertures at A B and C D are closed ; but when raised, as 
\n the figure, they are open. Let now steam be proceed- 
ing from the boiler in the direction of the arrow S ; if the 
apertures at A B and C D are closed, it can proceed no 
farther than the outside of the casing ; but if open, it can 
pass through all the vertical openings and down the steam- 
pipe C L, entering at both the upper and lower annular 
orifices. A small vertical motion, therefore, of the valve- 
rod will be enough to give a large aperture, for steam, 





1 




B 



122 THE ENGINE. ^ 

and the valve will open witli comparatively inconsiderable 
force. 

The common throttle-valve is, however, probably equally 
useful : see page 118. It answers the same end as the 
Cornish valve in cutting off the steam, and is a tTulj-hal- 
anced valve, which is not strictly the case with the latter ; 
so that no force is necessary to open it, except in overcom- 
ing the spring that keeps it in its place, and that which is 
required to overcome the friction of the spindle. It may 
be objected against the use of the throttle-valve, that it is 
apt to be leaky ; but the leakage will at most be but tri- 
fling, sufficient perhaps to tell on an Indicator diagram (see 
" Indicator and Dynamometer," p. 26), but not so impor- 
tant as to be worth regarding when considered with refer- 
ence to the working of the engine. The throttle-valve is, 
moreover, a cheaper valve in the first instance, and is not 
so likely to get out of order : and probably, after a few 
months wear, the latter would be found equally leaky, for 
its seatings are very soon injured by the scales of iron be- 
coming detached from the valve-box. 

146. Equilihrium-valve. 
This valve, which is called the equilibrium-valve, is 
very valuable, because it unites all the properties of the 
Cornish double-beat valve, and is somewhat simpler. Its 
principle is easily understood by inspecting the accom- 
panying figure. E B F is the steam-pipe, and the arrows 
show the course of the steam proceeding from E towards 
F ; A B are two circular and conical valves on one spindle 
C D, and they are represented in the diagram raised up 
from their seats, so that there is a passage for the steam all 
round their edges ; but when the spindle is depressed by 
the machinery of the engine, the further passage of the 
steam is intercepted. It is evident, in this construction, as 
well as in the common Cornish valve, that a small motion 
of the spindle gives a large space for the steam. The 
upper valve A is made rather larger than the lower valve 



EQUILIBRIUM-VALVE. 



123 



B; that the pressure on its upper 'side may predominate 
and keep it firmly in its seat. 




147. Equilibrium-valves as fitted to H.M.S. Penelope, 
It is difficult to gain a very clear conception of the 
arrangement of these valves without a model; but the 
following description may be of some service. Each cyl- 
inder has four equilibrium valves, represented by A, B^ C, 
D, in the figure. Two of which, viz., A and C, serve for 
the admission of steam, and the other two, B and D, for 
the exhaust ; S S is the steam-pipe, E E the eduction-pipe. 
A transversal section of A and B is shown below, and the 
passage leading to the upper port in the former, and from 
the port in the latter. When the valves on the spindle at 
A are raised, the steam passing through the orifices pro- 
ceeds in the direction of the arrow, as shown at F, to the 



124 



THE ENGINE. 



upper side of the piston ; again, as the valves on the spin- 
dle at B are raised, the steam leaving the npper port pro- 




ceeds, as is shown by the arrow at G, through the orifices 
down the eduction-pipe E, and so to the condenser. 

148. The Gridiron-valve. 
This valve receives its name from its shape and appear- 
ance, and serves the same purpose 
as the Cornish double-beat valve, 
viz., that a small motion of the 
valve produces a considerable 
opening. Let A B C be three port- 
ways in the plate of metal DE, 
through which it is desirable to 
allow the steam to pass at certain 
intervals. If now another plate of metal of the same size 
and shape be placed on this, so that the orifices corres- 
pond, a free passage will be left for the steam through each 




MAU DSL ay's valve. 



125 



orifice ; but if the second plate be moved up a sligbt space, 
until the orifices in the one plate are opposed to the solid 
metal in the other, the passage will be intercepted at each 
port-way at the same instant, and the communication will 
be cut ofi". It will be readily per- 
ceived that this contrivance gives 
three times as great an opening 
for steam, with the same motion 
of the rod, as would have been 
produced if there had been only 
one port-way. And consequently 
the depth of the port- way need only 
be one-third what would otherwise 
be necessary. 



S=^ 



149. Other kinds of Expansion valves. 

The common throttle- valve is fre- 
quently fitted for this purpose, as 
in H.M.S. Edinburgh; it is either 
a rectangular or circular valve with 
a spindle across its centre, acted on 
by a crank on the outside, to which 
is attached a weight or spiral spring, 
so as to close the Orifice after the 
expansion-cam has opened it. This 
valve is marked C in Plate I. 



150. Maudslay and FieMs Rotary 
Expansion-valve. ' 

The form of this valve is the 
same as that of the common throt- 
tle-valve (see plate, p. 127) ; but, in- 
stead of having a reciprocating ac- 
tion, it rotates in the steam-pipe, 
thus opening and closing the orifice 
alternately. " 

To show how this is effected, and the mode of adjusting 
it to give any required amount of expansion, let A A be 




126 



THE ENGINE. 



a spindle, which has a slot-way g for some portion of its 
length ; B is a holhw spindle, continued to the right, to 
the extremity of which the valve is fitted, as represented 




in the diagram on the preceding page. In this spindle 
also there is a slot- way, not in the direction of its length, 
but forming a spiral upon it, as shown at B. Now, it is 
easily seen that when a feather passing through both slot- 
ways connects these spindles together, the position the valve 
will occupy in the steam-pipe will, relatively, depend on 
the part of the spiral slot- way brought by means of the 
feather in connection with the other slot- way in the spindle 
A A. This is' effected by the following contrivance : The 
screw f is worked by the handle D, and thus moves a col- 
lar C. This collar carries with it the feather ; and it will 
be perceived, that as this feather, which passes through 
both slot- ways, travels to the left, the outer spindle, as also 

the valve, will commence 
rotating in opposition to the 
hands of t watch, and vice 
versa, if the screw be turn- 
ed in the opposite direc- 
tion; and therefore the 
positions of the two spind- 
les become shifted with relation to each other. Having, 
by these means, set the valve, here shown, so as to cut off 




BAROMETER-GAUGE. 



127 



the steam at any portion of tlie stroke, tlie whole is made 
to revolve by a pair of wheels G and H (see Fig. p. 126). 
G- is a wheel gearing into H, and admits of being connected 
with or disconnected from the engine-shaft S by means of 
a lever m. F is a fore and aft shaft, terminating at h, where 
a pair of bevelled wheels communicate its motion to the 
valve-spindle at right angles to it. e and d are levers act- 
ing upon the clutch c to connect or disconnect the expan- 
sion-gear. One other particular requires explanation. A 
di£B.culty would evidently arise in setting the slide to work 
expansively from the circumstance 
that the earlier the steam is cut off, 
the earlier it would be readmitted. 
This is provided against by giving 
the slide considerable thickness, so 
that it may close the orifice during 
some considerable portion of its rev- 
olution, as in the annexed figure; 
care being taken that the valve 
when working at its highest grade 
of expansion shall open for steam 
before the slide has cut off the 
steam. 




151. Barometer or Condenser- gauge. 
The gauge for ascertaining the state of the vacuum in 
the condenser is so called, because its principle and mode 
of action are similar to that of a weather-glass, having a 
small quantity of air in the upper part of the tube. The 
principle of the weather-glass is as follows : A glass tube 
33 or 34 inches long is filled with mercury, and then (the 
orifice having been stopped with a finger) it is inverted 
over a basin of mercury. The finger is then taken away, 
and it will be found that the mercury will immediately 
sink in the tube, and consequently rise in the cistern, till 
its weight balances the pressure of the atmosphere, which, 
9 



128 



THE ENGINE. 



by its elasticity, is endeavoring to force it up the tube. 
And it will be found that the height of the mercury in 
the tube above that in the basin is about 80 inches, vary- 
ing slightly from day to day according to the state of the 
atmosphere. Now, in order to show how to make this 
principle available for a condenser-gauge, we will next 
conceive that some air has made an entrance into the up- 
per portion of the tube ; the pressure of this will assist 
the mercury in counterbalancing the atmosphere, and there- 
fore the mercurial column will not be so high as it other- 
wise would have been ; and we can further perceive, that 
the greater the pressure of the air above the column, the 
shorter that column will be. Hence we can use this in- 
strument, not only to exhibit the pressure of the external 
air, but likewise the elasticity of any gaseous fluid ad- 
mitted above the mercury in the tube. This, then, is the 
method of using the mercurial column in connection with 

the condenser ; for we 
have only to make a 
communication with the 
upper part of the glass 
tube and the condenser, 
and the pressure of the 
steam in the condenser 
will be discovered from 
inspection by observing 
how much the column is . 
belc^ what it would 
have stood at had a per- 
fect vacuum existed. The 
contrivance by which 
this is effected is as fol- 
lows: A CD is an iron 
tube, open at A, and 
communicating with the 
condenser at D ; C is an iron cup surrounding the tube, 




BAEOMETER-GAUGE. 129 

and filled with mercury ; G is a stop-cock ; E F is a glass 
tube, open at tlie lower end F, but closed at E. When 
this glass tube is placed over the iron tube A C, the end 
A is near the top of the glass E, while the open end of 
the glass F stands in the mercury-cup C ; and while the 
stop-cock G is closed, the mercury does not rise in the 
glass ; but (supposing a partial vacuum in the condenser) 
directly G is opened, there will be the same amount of 
vacuum in the tube as in the condenser, and the atmos- 
pheric pressure on the surface of the mercury in the cup 
will force it up the space between the two tubes, till a bal- 
ance of forces is produced, when it will rise no higher. A 
piece of cork should be inserted in the upper end of the 
tube A C, to prevent the descent of the mercury into the 
condenser, which it is apt to do if there is not sufficient 
mercury in the cup to form a column whose height will 
balance the pressure of the air, or in the event of the ves- 
sel rolling. The cork is usually porous enough, if not 
pushed in hard, to allow the communication to be kept up ; 
but if not, a small hole must be made in it. 

152. To estimate the Pressure hy the Barometer-gauge. 
Since 30 inches of mercury press downwards with the 
same force as the atmosphere (which, in round numbers, is 
15 lbs. on the square inch), therefore every two inches of 
mercury correspond to 1 lb. pressure ; and consequently, 
wishing to estimate the pressure, a scale of inches is fixed 
by the side of the glass tube, the number of inches on the 
scale being supposed to be measured from the surface of 
the mercury in the cup ; but as the vacuum is supposed to 
be tolerably good while the engine is working, the scale is 
only graduated for a few inches below 30. If, then (after 
what has been said), the mercury stand at 28 inches, the 
pressure in the condenser is 1 lb. ; if at 26, it is 2 lbs. ; if 
at 24, 3 lbs., and so forth ; every fall of 2 inches denoting 
an additional pound of pressure in the condenser. 



130 



THE ENGINE. 



153. Errors in the 'preceding Mode of estimating the Vacuum, 
There are two sources of error. In the first place, the 
pressure of the atmosphere in the cup is always liable to 
change ; this is, however, not a very important defect com- 
pared with the following. For, as was said in describing 
the scale, the graduations are made on the supposition that 
the level of the surface of the mercury in the cup is sta- 
tionary, because it is from this level that the scale com- 
mences ; and therefore a fixed scale must be erroneous, on 
account of the sinking of the mercury in the 
cup as it rises in the tube. In the weather- 
barometer this defect is sometimes remedied 
by taking care that each adequate fraction of 
an inch shall be graduated as an inch ; but 
the same process cannot be adopted here; 
for the glass tubes being liable to accidents, 
they are at times replaced by others of larger 
or smaller bore, and this would completely 
frustrate all attempts at accuracy by these 
means. Another cause of errqr will arise if 
any of the mercury be lost from the cup by 
accident ; for by such means the scale may 
be wrong as much as an inch. 

This error arising from the rising and fall- 
ing of the mercury -level in the cistern of the 
common gauge, previously described, can 
only be obviated by having a shifting instead 
of a fixed scale. The scale of inches A B, in 
Fig. 1, which is usually fixed to the framework 
of the engine, is detached, and a stout wire, 
B 0, of the proper length,* is fitted to it, and 
terminating in a pointer at C. Let, now, the 
^^S- ^' scale be allowed to slide in a groove, and 
when an observation has to be made, it must be moved till 



* That is to say, of such length that any number of inches on the 
scale may designate the requisite number of inches from C. 



SHORT GAUGE. 



131 



C comes into contact with the surface of the mercury in 
the cup. It will be convenient to have a small handle, as 
at A, to raise and depress it. 

154. Short Barometer -gauge. 

This error may also be corrected with sufficient accuracy 
by having a barometer-gauge precisely similar to what a 
weather-barometer would become if it were quite enclosed 
in ia space communicating with the condenser ; it would 
then be found that, before a vacuum was created, the mer- 
cury would stand as high in the glass tube as in the 
weather-barometer: but on creating a vacuum, and thus 
taking off the pressure from the mercury in the cistern, the 
mercury would fall in the tube. In this instrument, there- 
fore, the less the height of the mercury in the tube the 
better the vacuum, whereas in the common gauge the 
reverse was the case. 

This is the principle of what is called the short barome- 
ter, of which Fig. 2 is a representation. A 
is the cistern, which communicates with 
the condenser by means of .the tube B E, 
having a stop-cock at B. C D is a short 
tube opening into the cistern A, but closed 
at C. The dark part is supposed to be 
filled with mercury. Now, as the vacuum 
is created above A, the reaction of the 
glass at the top of the tube at C will be- 
come less, till (the vapor not being able to 
sustain the whole column C D) it will begin 
to descend ; and, leaving a pure vacuum 
at the upper end, will give the actual 
pressure. This barometer i-s made short, 
because the upper extremity would be of ^^* ' 

no service, since the instrument is only used when a partial 
vacuum has been attained. 

155. Lubricators. 
These are brass cups or vessels, into which oil is put to 




132 THE ENGINE. 

lubricate the bearings and otlier moving parts of the ma- 
chinery. The object of lubricators is to have the bearings 
lubricated gradually, and prevent the necessity of oiling the 
bearings so very frequently as the engineers were com- 
pelled to do before their introduction. The common kind 
consists of a cup with a tube passing through the bottom, 
and rising nearly to the level of the upper edge. Five or 
six worsted threads pass down this tube, and their upper 
ends hang over into the cup, which is kept supplied with 
oil, into which the worsted dips. These threads form, there- 
fore, what is called a cajpillary syphon, and the oil, by the 
capillary action, creeps up the worsted into the tube, and 
runs out of the lower end by drops. This end is placed in 
a hole of the engine communicating with the bearing, and 
thus it becomes incessantly lubricated, so long as the lu- 
bricator is supplied with oil. 

156. Expansion-gear. 
Where expansion-gear is fitted, the expansion- valves are 
closed and , opened by cams (as they are called).* These* 
cams are for the purpose of instantaneous action, which an 
eccentric does not give. The description of the eccentric 
shows that it opens an orifice but slowly, and closes it in 
the same manner. The steam during this process is said 
to be wire-drawn ; in other words, it is passing through an 
orifice becoming gradually narrower or wider. To gain 
the full benefits of expansive working, however, it is thought 
better to shut off the communication with the boiler as sud- 
denly as possible. Let us, then, imagine the expansion- 
valve to be kept on its seat by means of a spring or weight ; 
and that a lever E connects the expansion-valve with the 
expansion-rod levers F F, to which the pulley G is con- 
nected. The spring will therefore always keep the pulley 

* The slides themselves of some of Messrs. Seaward's engines are 
worked by cams instead of an eccentric, and thus do away with the 

necessity of expansion-gear. 



EXPANS LOIS'- GEAR. 



13S 



In contact witb the shaft. The diagram, however, shows 
that the portion of the shaft under the pulley G is not uni- 
form ; but that a part of the circumference is raised about 
an inch above the general level. There is a series of these 
elevations, B B, etc., each of which is called a step of the 





cam, and the portion of the circumference of the shaft they 
occupy becomes less and less as we proceed from right to 
left ; so that the end view of the shaft is represented by K, 
1 1 being a representation of the collars which are exhibited 
in the first diagram by C C. Now, as the shaft revolves, 
whenever any one of the steps B comes under the pulley, 
the pulley is pushed back, and the levers F F acting on 
the expansion-rod E, opens the expansion-valve ; but im- 
mediately the raised portion has passed the pulley Gr, the 
spring re-acts, and closes the valve again. It will be seen 
that the engineer, by turning the handle I, can bring the 
pulley into contact with any one of the steps at his discre- 
tion, and thus can regulate the portion of the stroke during 
Avhich the valve shall be open. When the pulley is in the 
position represented in the figure, the expansion-valve will 
be open during a considerable portion of the stroke ; and 
the engine is^ said to be working on a low grade of expan- 
sion. Some engines have as many as seven grades, others 
have but two. Jt is a practice with some engine-makers 
to arrange their expansion* in the following manner : Let 
the stroke of the engine be 6 feet, and let the steam be cut 



134 



THE ENGINE. 



off, if working most expansively, wlien the piston lias 
traversed one foot ; by the next step let it be cut off when 
the piston has traversed two feet, and so on, till we arrive 
at the point where the slide itself cuts off the steam, which 
is called the fixed expansion, and is beyond the control of 
the engineer. Students should take an early opportunity 
of inspecting the expansion- gear, as both description and 
drawing will fail to supply the place of information gained 
by actual inspection. 

157. Feed-pumps, 

As the water during its ebullition is continually being 
expended, its place must be supplied by a fresh accession 
from some other source. The supply might be kept up by 
the boiler hand-pumps, as they are called — that is to say, 




by pumps worked by hand forcing water into the boiler ; 
but to obviate the necessity of manual labor, there is, con- 
nected with each engine, and worked by it, a feed-pump, 
whose duty it is to send a jet df water into each boiler at 

e^iery stroke of the engine. The feed-pump is of greater 



• FEED-PUMPS. 135 

capacity tlian is absolutely necessary to supply the waste 
by evaporation in the boiler together with the amount of 
water blown out, in order to have a reserve that would be 
necessary in case the boiler were leaky. The quantity that 
can be supplied is usually from three to four times that 
consumed by evaporation. The feed-pump is a forcing- 
pump, with solid plunger, as at a ; having a valve, called 
the foot-valve, h, for allowing the admission of water to the 
barrel on the up-stroke, and a second valve, called the de- 
livery-valve, c, through which the water, thus admitted, 
passes as the plunger makes its down-stroke. The water, 
after passing through the delivery- valve, is conveyed by a 
pipe d, called the feed-pipe, to the boiler. There is a cock 
at the farther end of this pipe, by which means the supply 
to the boiler can be regulated. Now, since this cock may 
be partially closed, it will sometimes happen that the pump 
will raise more water than can pass through the orifice. A 
valve/, contrived to obviate this difficulty, is called the 
surplus or overflow valve.* This valve is kept in its place 
by a weight g, or spiral spring ; and when at any time the 
. water cannot escape freely into the boiler, it acts, by its 
increased pressure, on the under-surface of this valve, opens 
it, and either returns to the hot- well, from whence it came, 
by the pipe A, or is directed into the waste-pipe of the 
engine, and so goes overboard. There is a small stuffing- 
box at i, to keep the valve-spindle water-tight, as also one 
for the plunger at h. The feed- water is usually taken from 
the hot- well, because the water there is fresher than com- 
mon salt water, being mixed with the condensed steam, and 
also because it is warmer, the temperature of the hot- well 
being about 100°. The surplus-valve must be loaded to 
a greater amount per square inch than the pressure of 
steam in the boiler, to insure the passage of water when 
the cock is open. Some feed-pumps are fitted with valves 
in a bucket similar to the air-pump, instead of having a 
i^ • 

* This valve is sometimes called the escape-valve of the feed-pump. 



13t) 



THE EXGIXE. 



solid plunger ; tliese act, therefore, on tlie lifting instead of 
the forcing principle. In the old side-lever engines, the 
plunger of the feed-pump is worked by the cross-head of 
the air-pump. 

158. Bilge-pumps. 
Since water is always finding its way into the bilge, even 
if the vessel be not leaky, from the jackets of the cylinders 
(when fitted), from the various cocks opening into the en- 
gine-room, and, Avhen the engines are stopped, from the 
water driven out of the snifting-valve on blowing through ; 
therefore a pump, called a bilge-pump, is fitted to each 
engine, for the purpose of keeping the bilge clear. It is 
generally of the same kind as the feed-pump*; that is to say, 
it is a plunger-pump, with its foot-valve and delivery- valve.' 
In the accompanying diagram A represents the plunger, 

B the foot- valve, C the de- 
livery-valve, D a rose-head 
surrounded by the water 
of the bilge, B D is called 
the suction-pipe, C E the 
delivery-pipe. The plunger 
is mostly worked by the 
air-jpump cross-head, on the 
opposite side of the engine 
to the feed-pump. In 
some cases, the pump dis- 
charges the water by a pipe 
into the hot-well ; in others, the pipe leads directly over- 
board. This latter plan is much to be preferred, for the 
pump is apt to bring up solid substances, such as pieces 
of chip or oakum ; and if the valves in the valve-box be- 
come gagged up with any thing of this kind, the pump 
offers a free communication, through which the contents 
of the hot- well will find their way into the bilge. This 
has, at times, been attended with some inconvenience, the 
water getting into the after-hold, damaging the stores, etc. 




PADDLE-WHEELS. 137 

In one ship tlie water was nearly up to the fires before the 
cause of the mischief was discovered. 

Where the bilsje-pipe is carried directly overboard, the 
end of the pipe should be considerably above the water ; 
for when the ship is deeply immersed, the water may, by 
the rolling of the ship, be driven down the pipe, and if 
the valves happen to be up, it will pass into the bilge. 
Where the pipe is brought near the surface of the water, 
it is a good plan to have a cock fitted in the upper pipe, 
so as to cut off the communication with the sea. The suc- 
tion-pipes of the bilge-pumps, and indeed all other pipes 
in the bilge, should be of copper, and fitted with brass 
flanges and copper bolts. Lead pipes have been used for 
bilge-pumps ; but they are apt to choke up, and are easily 
bent and damaged. 

159. Modes of Propulsion. 

There are two methods of rendering the force of steam- 
engines available in propelling vessels, viz., Paddle-wheels 
and Screws. 

160. Paddle-wheels. 

The general construction of the common paddle-wheel 
is so simple, that scarcely any one who has ever seen a 
steamer finds any difficulty in comprehending it ; and in- 
deed it is understood by most people who scarcely com- 
prehend any other part of the machinery. We have 
already called the shafts qq the paddle-shafts. If there be 
but one engine to the vessel, as is the case with H.M.S. 
Bee, these shafts protrude beyond the sides of the vessel, 
and sustain a circular framework of iron to which rectan- 
gular boards, called paddles, are fastened; these boards 
being placed at equal distances round the circumference, 
and radiating from the centre.* As the crank causes the 
shafts, and therefore the wheels also, to revolve, the pres- 

* The diameter of the wheel is generally about eight times the 
length of the crank ; and the number of paddles is nearly the same 
as the number of feet in the diameter. 



138 THE ENGINE. 

sure of tlie boards against tlie water causes a reaction to 
be exerted, wbich becomes effective in propelling the ves- 
sel. If they revolve in one direction, the vessel goes 
abead ; and if in the contrary direction, tbis motion is 
checked, and she goes astern. The paddles are secured to 
the radiating arms of the wheels by hook-bolts, a species 
of bolt by which they are hooked on to the arms of the 
wheels, and can be detached when convenient. The pad- 
dles are generally made of one single board, but at times 
they are divided into two, and sometimes into three, by 
horizontal sections. "When the board is divided, it is for 
the purpose of setting the parts that are farthest from the 
centre on the opposite side of the arms to those which are 
nearer ; so that they are arranged on each arm like a 
series of steps, the lower one being on the after part of 
the arm, when entering the water, and the upper at the 
back of the arm.* Each portion of the paddle is then 
supposed to dip nearly into the same place in the water 
When two engines are used, as is the case with almost all 
the vessels in our steam navy, the shaft connecting the two 
engines together is called the intermediate shaft, and the 
shafts attached to the wheels are called the paddle-shafts. 

161. Feathering-paddles. 

Besides the common paddle-wheel, there are ot^hers with 
what are called feathering-paddles ; the object of these 
being to enable each paddle to enter and leave the water 
nearly in a vertical position, and thus avoid the loss of 
power caused by the obliquity of the common paddle- 
wheel. 

162. Beefing the Paddles. 

When the wheels are teo deeply immersed, the paddles 
may be disconnected from the paddle-arms and secured 
again nearer to the centre of the wheel : this process is 

*This wheel is usually called the cycloidal wheel, because the 
boards are arranged in that curve on each paddle arm. 



DISCONNECTIN-G. 139 

called reefing the paddles. Any method of doing this 
with ease and rapidity would do away with one of the 
chief objections to paddles, viz., the difficulty of preserving 
the same immersion of the paddle as the ship'h draught 
varies. 

168. Disconnecting the Wheels. 
Most vessels are fitted with means of disengaging- the 
wheels from the engines whenever it is intended that the 
ship should sail without steaming, to prevent the resist- 
ance the paddles would exert while being dragged through 
the water. Many engine- makers have plans of their own ; 
but others use a plan called, from its inventor, Braith- 
waite's disconnecting-strap, which will be given in the 
next article. 

164. Methods of disconnecting Paddle-wheels. 

1. Maudslay's Method. In this plan the wheel, the pad- 
dle-shaft, and the crank with which the paddle-shaft is con- 
nected, are drawn from the engine in a lateral direction, 
till the crank-pin, which, when the engine is at work, con- 
nects the two cranks together, ceases to be in contact with 
the paddle-shaft crank, and therefore the wheel may re- 
volve freely. If this plan be adopted, the paddle-boxes 
must be a few inches wider than otherwise would be neces- 
sary, to allow the wheel to be pushed out far enough. 

2. Sea ward's Methods. 1. There is a boss on the end 
of the paddle-crank, which, when turned, in a particular 
direction by levers provided for that purpose, allows the 
crank-pin to escape from the boss. 2. A slot- way is cut 
through the face of the paddle-crank, and the pin is re- 
tained in it by two bolts which run up the crank on each 
side of the pin, their heads being in sight close to the pad- 
dle-shaft. When these are withdrawn far enough, the pin 
escapes through the slot-way, and the wheel: is free to 
revolve. 

3. Braithwaite's Method. To understand this method, 
conceive the pac?c^?e-crank to be a complete disc, having the 



1-iO THE ENGINE. 

paddle-s"haft for the centre. The intermediate shaft hag 
the usual crank, the pin of which is attached to a ring 
passing round the disc, in the same manner as the ring of 
the eccentric surrounds the pulley. Now while the ring 
fits loosely on the disc, the engines or paddle-wheels may 
revolve independently of each other ; but if a key be so 
fitted as to connect the ring with the disc, which it does by 
friction, the wheel must revolve with the engine. It is 
found, in practice, that when disconnected, there is a great 
deal of friction to be overcome between the disc and the 
ring; and that when connected, it is difficult to connect 
them so firmly by the key as to prevent all motion of the 
disc in the ring. The ring is fitted with a key, half into 
itself, and half into the discs, in the same manner as the 
cranks are secured to the shafts. 

165. The Immersion of Paddle-wheels. 
The paddle-wheels of sea-going steamers should be 
about one-sixth of their diameter immersed in the water. 
For river-boats, the upper edge of the lowest paddle 
should be what is termed a-wash, or on a level with 
the water. In giving this rule, we are, however, suppos- 
ing the boilers' productive power to be proportioned to 
that immersion. But if that be not the case, we must be 
guided by it : what we must aim at is, to use up the steam 
supplied by the boilers without urging the fires, so as 
neither to let a great quantity escape on the one hand, nor, 
on the other, to allow the steam-pressure in the boiler to 
fall below its proper standard. 

166, Paddle-wheel Brakes, 
The most common description of brake is the friction- 
strap, which, by the application of a tackle, is pressed on 
the shaft ; but this is not found to be sufficient in a sea- 
way. The best method is that which consists of wedges 
driven, or rather screwed down, between the outer segment 
of the wheel and the paddle-heams. 



GOVERNORS. 145 

177. Governors in Screw-vessels. 
The principle of this apparatus is the same as that of 
the land-engines, being a machine for controlling the 
throttle- valve as occasion requires. Two heavy balls are 
suspended by means of arms to an axis revolving with the 
engines. The upper ends of these arms are jointed to the 
axis, and therefore as the axis rotates the balls will fly out 
from it ; and their distance from the axis will depend on 
the velocity. .The arms by which the balls are suspended 
are connected with rods, which give motion to the throttle- 
valve, and are so arranged that as the engines move faster, 
and therefore the balls fly out farther, the valve shall 
begin to close ; and if the engine relax in its speed, and the 
balls droop towards the revolving axis, the valve will open. 
Governors are sometimes fitted to screw-steamers of light 
draught of water, to limit the supply of steam to the cylin- 
ders when the ship pitches. For since the propeller is at 
one extremity of the vessel, it will at times, by the pitch- 
ing of the ship, be performing its revolutions in the air : 
the engines will then be relieved' of their load ; and if the 
supply of steam were not reduced, they would fly off' at a 
great velocity, which would again be checked as the stern 
of the vessel became immersed in the water. This would 
be detrimental to the machinery. The governor is so ad- 
justed that when the speed of the engines is much above 
what ought to be their maximum, the throttle- valve closes, 
and admits no more steam till the revolutions decrease, and 
thus lessen the centrifugal force acting on the balls. 



CHAPTER TV. 

178. Direct-action Engines. 

A DIRECT- ACTION engine is one in which the piston pro- 
duces a rotary motion of the crank without the interven- 
tion of sway-beams or side-levers. 

These engines are so varied in their forms and in the 
adaptation of their parts, that no general outline can be 
given. Scarcely any two are alike : but some are more 
commonly in use than others, and we shall therefore give 
such a description of these as will enable the reader to 
form an adequate idea of their construction ; remarking, 
at the same time, that such information as can be gained 
by books will not supply the place of personal inspection. 
The kinds of direct engines most commonly introduced 
into our steam-ships are those which have received the 
following names : 
Gorgon engines. 
Fairbairn's engines. 
Double-cylinder engines. 
Oscillating engines. 
Trunk engines. 
These engine^ are for propulsion by means of paddles. 
We have also every modification of these for driving the 
screw, the chief difference being that the same kind of 
engines for such purposes is placed with its cylinders 
horizontal, and the power is either applied in a direct 
manner to the screw-shaft or by means of gearing. 

It must be understood that the internal arrangements 
are the same in these as in the side-lever engines, all of 
them having cylinders, in which the steam causes the pis- 
146 



GORGON ENGINES. 147 

ton to move from tlie one end to the other ; as also con- 
densers, air-pumps, etc. The principal difference, there- 
fore, between them lies in the means by which the power 
exerted on the piston is transmitted to the crank, and in 
the configuration of the several parts ; the chief object 
proposed by the manufacturers being to confine the space 
occupied by their engines within the narrowest limits. In 
most engines of this kind, however, the connecting-rod is 
necessarily short. 

179. Gorgon Engines."^ 

The principle of construction of these engines will be 
more clearly seen by reference to the accompanying figure, 
which represents a section of one of such engines ; and the 
several parts are, for simplicity's sake, represented only by 
lines. Here A B C D represents the cylinder ; F is the 
centre of the shaft, directly over the middle of the cylinder 
(and therefore the engine is of the class called "direct- 
action") ; I E is a section of the piston ; I H the piston-rod, 
working steam-tight in a stuffing-box at K ; H G is the 
connecting-rod, and G F the crank. It is easily seen, that 
as the piston is forced up and down by the steam, the crank 
will be made to revolve, and consequently cause the paddle- 
wheel to rotate. The remaining parts of the engine will 
be readily understood : L is the condenser, M the air-pump, 
N the hot-well, a and h are the foot- valve and delivery- 
valves respectively, and c is the snifting-valve. There are 
two particulars deserving special notice in this engine, viz., 
the slides for admitting the steam and allowing it to escape, 
and the parallel motion, or the means of keeping the pis- 
ton-rod in its vertical line. It is observable that there are 
f^ur sides, viz., A, B, C, and D : two of which, A and C, 
are for allowing the ingress of steam ; and the other two, 

* The following ships are fitted with this kind of engines : Ardent, 
Caradoc, Cyclops, Driver, Firebrand, Geyser, Gorgon, Penelope, 
Polyphemus, Prometheus, Sidon, Styx, and Vixen. 



148 



DIRECT- ACTION ENGINES. 



B and D, for allowing it to escape to the condenser L * 
The following is an outline of the parallel motion : H is 
a beam called the " rocking-beam," one end of which is 
fitted to the upper extremity H of the piston-rod. P Q is 
a vertical frame, called the " rocking-standard ;" the lower 




end of this is connected with some convenient point Q, 
about which it can move, and the upper end P will there- 
fore describe a small circular arc about Q; but this arc 
will be so small, that it may be practically looked upon as 

* See d(^scription of these slides. 



GORGON ENGINES. 



14'9 



a straight line. T S is a radius-bar, attached at one end T 
to the framework of the engine, and at the other to the 
rocking-beam. If now these rods have the proper propor- 
tions, the motion of H will be vertical. The parallel mo- 
tion will be investigated completely in the next article. The 
rocking-beam is continued along to 0, and the air-pump 
rod is fitted to it by means of the intermediate rod E 0. 
The air-pump rod is kept, in a vertical line by means of 
guides. 

180. To find the Length of the Radius-rod, etc., of the Gorgon 

Engine. 
Let T S be the radius or bridle-rod, H P the rocking- 




beam, P the point to which the rocking-standard is con- 
nected, S the point of attachment of the radius-bar ; then 
it will be found that S P is a mean proportional between 
TS and HS; that is to say, TS:SP::SP:SH (1).* 
Also, if we wish to get the actual length of T S, S H, and 
S P, we shall have 



* This may be proved as follows : 

Let TS=a, SH=6, SP = c, SR=aj, H V=z. 



Then 



TR==x/TS^— SR«=-^a^ 



:a--nearly. 



Also SV=^HS^—HV^=v/Z>'—2'=6— ^nearly. 

TK=TR— YS=-a— 6— ^4-^nearIy. 
la 26 



150 DIBECT-ACTION ENGINES. 

(HP + T K)- 

TK + 2HP '''-''' W 

_ HP' 

^^""TK + 2HP (^) 

HP(HP + 2T K) * 
^ TK + 2HP ^^ 

and having T K and H P given, we may by these formulae 
find the length of the radius-rod, and the point S, to which 
it is to be fitted. 



But TK=a — b, because the point H will coincide with K when 
the engine is at half-stroke. 

of 2' 03^ a 

Again, since, by similar triangles, 

» X ^ X c 

b c ' ' z b 
x" c" 
"^^ ^ = ¥ 

Hence p = ^ 

or c^z=a.b 

and.-. SP^ = TS.SH 

.•.TS:SP::SP:SH, which proves .... (1) 
Again, let H P = w, T K = n, (known quantities) 

b-{-c=m (a) 

and a — b=n • (J^) 

also we have proved that c^=ab (y) 

b-\-x/cib = m .... by (o) and (y) 
or v^&(>/6-4- v/a)=m 

also (-v/a— v/&) (\/a+\/fc) = ». .by(j3) 

\/b m 

x/a — \/b "^ n 
hence v^6=i»v/a — m^b 

m-i- n 

But a — = n 

(w -4- ny 






FAIKBAIRN'S ENGINE. 



151 



181. FairlaMs Direct- Action Engines!^ 
The chief peculiarity of these engines is in the parallel 




motion, which, after all, is somewhat similar to that of the 
Gorgon engines. 

The dotted lines represent the Grorgon engines. H P 



^- 



Again, 
Also, 



or 

that is, 
SH = 6 



a{n^-\-2mn) 



= n 






TS: 



TK+2HP 



mr 



HP^ 



{m-\-ny n-\-2m TK+2HP 



SP^ = SH.ST = 



HP^(HP-f TK)^ 



SP 



(TK + 2HP)'' 
HP.(HP + TK) 



(2) 

(3) 

(4) 



TK-f2HP 

* The following ships are fitted with this kind of engines : Dragon, 
Odin, and Yulture. 



152 DIBECT-ACTION ENGINES. 

is the rocking-beam, H the point to whicli the piston-rod 
and connecting-rod are attached, P the point of attachment 
of the rocking-standard ; then, to construct Fairbairn's 
parallel motion, let the rocking-standard P Q be inverted, 
as in the figure, so as to hang down from a point Q' in the 
entablature of the engine. In the Gorgon engines H P is 
prolonged to 0, as before described, and the air-pump is 
worked from this extremity ; but in Fairbairn's engines 
the radius -bar S T will be produced to some point 0', and 
OT serves as the beam for working the air-pump. The 
steam is admitted and allowed to escape by means of a D 
slide-valve, worked by an eccentric. 

The four main parts of each engine, viz., the cylinder, 
slide-valves, condenser, and air-pump, form a square, and 
thus occupy the least possible area. 

182. Maudslay's Douhle- Cylinder Engines."^ 
In the foregoing direct engines the connecting-rod is 
necessarily shorter than it would have been if side-levers 
had been used ; and consequently the force exerted on the 
crank alters more suddenly as the motion is alternated from 
the down to the up stroke, and vice versa, than would have 
been the case had the connecting-rod been longer ; there- 
fore, although, as a mechanical principle, the whole force 
exerted by the steam in the up and down stroke is given 
off in each revolution of the crank, f still it has been ob- 
jected by many practical men, that these sudden and violent 
changes are liable to cause derangement in the machinery ; 
and also, from the shortness of the crank compared with 
the length of the radius of the paddle-wheel, the engine is 

* The following ships are fitted with this kind of engine : Devasta- 
tion, Hermes, Medea, Scourge, Terrible, and Osborn. 

t The mean effect produced through the intervention of a crank 
is the same as if ^^ of the pressure exerted on the piston had been 
applied at the extremity of the crank through the whole revolution. 
This may be shown thus : let P be the pressure on the piston, and 
Q be a power which, exerted at the extremity of the crank and at 



MAU DSL ay's engines. 



153 



more apt to be checked if struck by a heavy sea when near 
the top centre than it would if the connecting-rod and crank 
had been of greater length. ^ 

JS'ow in most direct engines a long connecting-rod is an 




impossibility ; for the distance from the shaft to the bottom 
of the vessel being limited, the depth of the cylinder, the 
radius of the crank, and the length of the connecting-rod, 

right angl^ to it, would produce the same effect : then P X 2 Z = Q 
X 2 nr ; where I == length of stroke, and r = radius of crank. • 



But 



nr 
r 
2 



Q -= - P = — P very nearly. 

7»» ii 



154 DIRECT-ACTION ENGINES. 

must all be accommodated to it. Messrs. Mandslaj and 
Field, seeing this evil, proposed to remedy it by adapting 
two cylinders to e^ch engine, instead of one ; the cylinders 
having one connecting-rod between them. In the accom- 
panying figures Ai and Ag are the two cylinders of one of 
the engines ; ^i ^2 the piston-rods ; these rods are connected 
together at their upper extremities by the cross-piece B C 
D, called (from its form) the T-plate or cross-head; the 
lower end C of the T cross-head is connected with the con- 
necting-rod C E, which again being connected with the 
crank E F, communicates with the paddle-shaft F. The 
condenser Gr is underneath the cylinders. It is clear that 
if steam be admitted below both pistons at the same time, 
the pistons, in rising, will force up the T cross-head, and 
with it the connecting-rod, etc. ; and conversely these will 
ag^in descend as the piston is forced down. Hence the 
working part of the engine can be comprehended. It re- 
mains to be shown how the steam is' admitted to both 
cylinders -simultaneously. Looking at the plan of the 
figure, the circle S represents a slide-valve, different in 
form from the common slide-valve, inasmuch as it is cir- 
cular instead of being semicircular ; it has one upper and 
lower face in contact with the ports of the cylinder Ai, 
and one of each in contact with the cylinder Aj ; so that 
as the valve is raised or depressed, the steam is admitted 
above or below both pistons at the same instant of time. 
H is the air-pump, the bucket of which is worked by the 
beam K L moving round the centre I. The slides being 
circular, admit of a simple kind of metallic packing, simi- 
lar to that of a steam-piston. The face or nozzle of the 
cylinder must of course be concaved. 

183. BouUon and Wattes Direct-action Marine Engines^ 
" In this plan of engine the condensers are situated be- 

* The following ships are fitted with this kind of engines : Centaur 
and Yirago. * 



OSCILLATING ENGINES. 155 

tween tlie cylinders, and at the extremity of eacli conden- 
ser an air-pump is situated. These air-pumps are wrought 
by a beam, the centre of which rests on the condenser-top, 
and which derives its motion from a crank on the inter- 
mediate shaft — a rod extending from this crank to one of 
the ends of the beam, which is made something of the bell- 
crank fashion, to communicate the moverxient. The top 
of the piston-rod is maintained in the vertical position by 
guides."* 

184. Messrs. Miller and RavenhilVs Direct-action Marine 
Engines.-\ 
"No engine can occupy less space than this, for its 
length is very little more than the diameter of the cylin- 
der. The condensers extend from cylinder to cylinder, 
having the air-pumps within them; so that the whole of 
the cast-iron part of the engine is bound together in a solid 
mass. The air-pump buckets are wrought by means of 
cranks on the intermediate shaft." J 

185. Oscillating Engines.% 
In these engines the connecting-rod is altogether dis- 
pensed with, the piston-rod being attached directly to the 
crank ; and because the piston-rod, from this mode of con- 
nection, must either be bent when motion ensues, or the 
top of the cylinder must move laterally, this is provided 
for by suspending the cylinder on two hollow trunnions, 
round which it can oscillate backwards and forwards as 
the crank moves from one side of the shaft to the other 
The steam from the pipe enters a belt on the cylinders 

* Artizan' vol. ii. p. 4. 
The following, ships are fitted with Miller and Ravenhill's direct 
engines : Gladiator and Rosamond. 

X Artizan, vol. ii. p. 4. 

§ The following ships are fitted with oscillating engines : Antelope, 
Banshee, Basilisk, Black Eagle, Oberon, Sphinx, Trident, Vivid, 
Fairy, Minx, Phoenix, Rifleman, Teazer, Wasp, etc. 



156 DIRECT-ACTION- ENGINES. 

througli the trunnions nearest the ship's side. From this 
belt it passes through the valve, by which means its dis- 
tribution is regulated, and escapes from the cylinder to the 
condenser by the trunnion on the opposite side to that at 
which it entered. There are two air-pumps, lying at an an- 
gle with the keel, and they are both worked by a single 
crank on the intermediate shaft ;* the due position of the 
air-pump rods being maintained by means of guides. The 
slide-valves are provided with guides, and are worked by 
means of an eccentric in the usual manner : but the eecen- 
tric-rod is not attached immediately to the valve-lever, but 
to a curved transverse link, guided between the columns 
that support the shaft, and susceptible of a vertical motion. 
T^e curve of this link is concentric with the arc described 
by the cylinder in its oscillations ; and its design is to ob- 
viate the distortion that would result from the combined 
movement of the cylinder and eccentric.f 

186. Engines for working the Screw- Propeller. 

These engines may be said to be of two kinds, viz., those 
having the axis of their cylinders vertical, and those whose 
cylinders lie horizontally. The former kind cause a long- 
itudinal shaft above the cylinder to rotate by means of 
cranks. This shaft is connected with a large driving- 
wheel, which, acting on a smaller wheel connected with 
the screw-shaft, causes it to revolve with a greater velocity 
than it would otherwise do. 

The second kind of engines consist of those whose cyl- 
inders are horizontal : these are destined to work the 
screw shaft direct, that is, without the intervention of any 
cog-wheels or gearing. They work at higher velocities 
than would be necessary if multiplying gear were used, 
and the shaft is made to revolve by means of cranks. The 
cylinders are mostly placed on difiTerent sides of the 

* In small engines the air-pumps are worked by an eccentric, 
t See Artizan, vol. ii. p. 92. 



SCREW-ENGINES. 



157 



shaft, as also the air-pumpS; etc. To avoid the wearing 
away of the cylinder by the weight of the piston, the pis- 
ton-rod is prolonged, and projects beyond the farther end 
of the cylinder :* so that the piston is supported by two 
stuffing-boxes, one at each end of the cylinder. The chief 
obstacle to be overcome by the manufacturers of these en- 
gines is, that on account of the narrow space in which the 
engines have to work, especially when placed low down, 
the cylinder is necessarily brought closer to the shaft than 
could be wished, and consequently all the difficulties aris- 
ing from the common direct-action system apply also here. 
These engines are mostly fitted with double eccentrics, for 
the purpose of rapidly reversing the motion, since this is 
more essential for screw-ships than for those fitted with 
paddles. 

187. Direct-acting Screw- Engines. 
There are several ships fitted with this class of engines. 
By inspecting the diagram it will be seen that A B, CD, 
are two cylinders lying horizontally on opposite sides of 
the screw-shaft whose section is S ; E and F are the pis- 
tons ; E G, H F, the piston-rods ; G L, L H, the connecting- 
rods, attached to the same crank S L ; and if the steam be 
in the portions of the cylinders A F C F, it tends to turn 




the crank in the direction of the arrows, and thus produces 
a revolution of the shaft. There are usually four of these 
cylinders, two on each side of the shaft ; but if two only, 
they do not work the same crank as in the diagram, or the 
engines would both be on the centre at the same time. To 



* This is not fitted in all cases. 



158 



DIRECT-ACTION ENGINES. 



give a tolerably long connecting-rod, tlie cylinders are 
placed as far from the shaft as can be done conveniently. 
The air-pumps of these engines are -usually placed under 
the main shaft, and worked from it by means of eccentrics. 
They are fitted with locomotive slides (Article 127), and 
are worked either with double eccentrics or two single 
eccentrics (Article 140).'^ 

188. Direct-acting Geared Engines for Screw-Ships. 
The accompanying diagram will suf&ce for a sketch of 




this class of engines. E F is a horizontal cylinder, of 
which A is the piston and A B the piston-rod ; B D the 
connecting-rod, turning the crank D 0, and with it the 
driving-wheel K Gr, which is geared to the pinion K H : 
therefore as this wheel revolves in the direction of the 
arrow, the pinion revolves in the opposite direction, as is 
shown in the diagram ; C is a section of the screw-shaft, 
and consequently by these means rotation of the shaft is 
produced. It is easily seen that this is the same kind of 
engine as the direct-acting engine for paddle-steamers, the 
cylinder lying horizontally, and the driving-wheel taking 

* The following ships are furnished with this kind of eng-ines : 
Ajax, Blenheim, Conflict, Desperate, Euphrates, Edinburgh, Hogue, 
Horatio, James Watt, Niger, Megsera, and Yulcan (worked with 
four cylinders) ; Amphion, Archer, Cressy, Tribune, and Princess 
Koyal (worked with two cylinders). 



TEUNK ENGINES. 159 

the place of the paddle- wheel. Grearing is introduced to 
increase the number of revolutions of the shaft, and thus 
enable the screw to make revolutions enough without giv- 
ing undue velocity to the piston. This kind of engine is 
therefore useful for driving screws of small diameter and 
fine pitch.* 

189. Oscillating Horizontal Engines. 
The accompanying diagram will show the application of 
the oscillating engine as fitted for screw-propellers. There 




are usually four cylinders, two pistons being coupled to 
each crank, as represented in the drawing ; and as is also 
the case with the. direct-acting horizontal screw-engines. 
In the diagram A and B are the two cylinders on opposite 
sides of the shaft, whose centre is C, the cylinders being 
allowed to oscillate about their steam and eduction pipes ; 
A D and D B are the piston-rods, which also serve as con- 
necting-rods, and unite in turning the crank C D, by which 
means the rotation of the screw is effected. The air- 
pumps are worked from the main shaft as in the direct- 
action engines, but are placed at an angle instead of being 
vertical, that they may be worked by one crank.f 

190. Trunk Engines. 
The cylinders of these engines are horizontal, and con- 
nected at once to the screw-shaft. Imagine a hollow trunk, 
ahcd, to pass through the cylinder A B C D and to pro- 

* The following ships are fitted with this class of engines : Duke 
of Wellington, Dauntless, Highflyer, and Sharpshooter. 

t The following ships are fitted with this kind of engines ; Simoom 
and Sanspareil. 
11 



160 



DIRECT-ACTION ENGINES. 



ject beyond it at botli ends, passing tlirongh tlie covers 
A Band CD. Where the trunk comes in contact, with 
the cylinder, a stuffing-box and gland are fitted to keep 
the trunk air and steam tight. The middle portion of the 




trunk is rigidly connected with the piston of the cylinder 
(represented by the shaded portion of the diagram), and 
to the central part E of the hollow space the connecting- 
rod E F is attached, which turns the crank F Gr of the 
screw-shaft G-. The piston surface becomes for this reason 
an annular ring. Now as the crank revolves, the crank 
end of the connecting-rod must vibrate ; and this it will 
be at free liberty to do, although there is no piston-rod, 
because the size of the trunk will admit of a vibratory 
motion within it. These engines are fitted with locomo- 
tive slides, and are worked with double eccentrics, render- 
ing the back and head turns at all times to be depended 
on. The air-pump, like the cylinder, is horizontal ; and, 
indeed, all the parts of the engines are as low as they can 
possibly be, for the purpose of bringing the machinery 
below the water-line. The air-pump is worked directly 
by the piston, the pump-rod^ e/^, passing through the 
• covers of the cylinder as represented in the diagram. The 
pipe shown in the figure, which is taken by many at first 
sight as the steam-pipe, is, in fact, the eduction pipe for 
conveying the waste steam from the cylinder to the con- 
denser. The principle of the air-pump, as it is not con- 
fined alone to this sort of engine, will be explained in the 
next article. 



MAUDSLAY AND FIELD'S ENGINE. 



161 



191. The Double-acting Air-pump. 

There are no valves in tlie bucket of this kind of pump, 
g being a solid piston, whicli is worked horizontally by 
the rod eg ] pq are foot- valves, and m n delivery- valves ; 
the lower chamber represents the condenser, and the upper 
one the hot- well. 

Suppose, now, the piston to be at the extreme left, and 
to commence moving to the right : if there be any water 
above g, it will be driven through the valve n into the hot- 
well ; at the same time the valve p will open, and allow 
the water of the condenser to pass through it ; on the re- 
turn-stroke of the piston, this water will be forced through 
m into the hot-well, and so on. Since this pump acts dur- 
ing the return-stroke, the area of the piston need only be 
half as great as that of the common description. 



192. Maudslay and FieMs Return Connecting-rod Engine. 
This engine takes its name from a peculiarity in the 
construction, viz., that the connecting-rod lies. between the 
extremity of the piston-rods and the cylinder, instead of 
being in the opposite direction. There are also two pis- 
ton-rods to each cylinder. Fig. 1 represents an end view 



Fig. 1. 



Fig. 2. 




of the cylinder, showing the cover, with the two glands 
c c for the piston-rods, and a recessed space g in the centre, 
to prevent the crank from striking the cover, li and li are 



162 



DIKECT-ACTIO^" ENGINES. 



the sections of two locomotive slides, with wHcli each en- 
gine is fitted. In Fig. 2 a a is a horizontal section of the 
cylinder, etc. ] hh is the piston ; c c the two rods, one work- 
ing above the shaft, and the other below it ; e e a sort of 
cross-head connecting the piston-rods. This cross-head is 
necessarily at an angle with the horizontal plane ; a is the 
connecting-rod, working the crank, as in the figure, and 
turning the screw-shaft//. With this kind of engine, it 
is clear that a longer connecting-rod may be adopted than 
in most cases of horizontal engines, because, although the 
cylinder is brought very close to the screw-shaft, yet the 
piston-rods may be prolonged on the opposite side to any 
convenient distance, by which means additional length is 
gained. 

193. Humphrey's Engine for Screw-Ships. 
The principle of construction of the engine will be easily 
understood by the accompanying diagram. Here a a is the 




cylinder ; & 6 the piston ; c the piston-rod ; a the connect- 
ing-rod ; e the crank turning the screw-shaft ; ^ is a rod 
also worked by the piston, and forming the air-pump rod 
for the double-acting pump g g, the construction and work- 
ing of which were explained in Art. 191. 



CHAPTER y. 

GETTING UP THE STEAM. 

194. Filling the Boilers. 

The first thing to be done is to get the water into the 
boilers. To do this, let the blow-out cocks and Kingston's 
valves be opened, and the water will of course commence 
running in. To prevent any obstruction caused by the 
pressure of the air in the boiler on the surface of the 
water, let the guage-cocks be opened ; and, as the water 
rises, the air will be driven through their orifices into the 
engine-room. If expedition be required, the safety-valve 
may be opened likewise until the water is up, to take the 
superincumbent pressure from the water : the water would 
evidently run in till it has the same level as that outside 
the ship. If the vessel be deeply immersed, so that too 
much would enter, let the blow-out cocks be closed, when 
the fires can be lighted with safety. In ships of light 
draught of water, the level of the water in the boiler must 
be higher than that of the sea ; consequently, when the 
water ceases to enter, the blow-out cocks must be closed, 
and the boiler hand-pumps set to work. We can ascertain 
when the water ceases to flow in of its own accord by put- 
ting the hand, or a lighted candle, to the orifice of the 
guage-cocks ; for if the safety valves be closed, air will 
rush out so long as the water rises, and will then cease. 

These remarks, however, apply principally to the case 
where an engineer is not well acquainted with his engine, 
boilers, etc. ; for, after once or twice filling, he knows with 
sufficient accuracy the time the wat«n' will be flowing in, 

163 



164 GETTING UP THE STEAM. 

and acts accordingly ; making due allowance for variations 
in tlie draught of water outside, depending on tlie load. 

195. To know when the Blow-out Cocks are closed. 
It is tlie practice of engine-makers to cut a slot-way or 
score across tlie plug of the cock in the same direction as 
the hole through it ; so that when this slot- way lies across 
the pipe, the orifice is necessarily closed; and when we 
wish to open it, the plug must be turned till the score lies 
in the direction of the pipe. 

196. On the Seight to which the Water is to he raised at first 
The steam will be got up most rapidly when the height 
of the water above the flues or tubes is not greater than 
it should be to ensure the safety of the boiler. Therefore 
the fires may be lighted as soon as the flues or tubes are 
all covered ; and when the water is an inch or two deep 
over them, the pumping need not proceed further for some 
little time ; and if the water be running in, it should be 
stopped till that within the boiler has gained a sufficiently 
high temperature. The chilling effect of the cold iron is 
detrimental to the effective combustion of the coal. Every 
one must have experienced the effect of putting on a quan- 
tity of cold coals on a fire that is nearly going out. The 
fire will probably be extinguished by the process that was 
intended to revive it. 

197. Laying the Fires. 
Unless the fires have been previously laid, this opera- 
tion is generally performed while the water is running up 
into the boilers. It is, however, mostly done after the 
fire-places are cleaned out and put to rights. It is done 
as follows : Let the fire-bars be covered with coals from 
one end to the other : this is done to prevent a current of 
cold air passing through the back of the ash-pit into the 
tubes, and to cause aU the air that enters the tubes to 
pass over the fresh lighted wood, etc. The coals being 



DUTIES TO ENGINES. 165 

arranged; some fire- wood is placed, in front; with some of 
the oily cotton, waste oakum, etc., put under it. Then, 
having set a light to the oakum, the ash-pit doors are kept 
shut, to concentrate the draught on the ignited part. In 
a few minutes the wood and the coals placed on the top 
will be thoroughly ignited. The upper part of the fire 
must now be pushed back over the new coal : and it will 
be striking to observe how rapidly the combustion will 
proceed, the blast of air over the upper surface of the 
coals carrying the heat and flame from mass to mass with 
great rapidity. When the fire has well burnt up, the 
ash-pit doors are opened, to obtain the greatest draught 
possible. 

198. When wishing to get up the Steam expeditiously. 
When in a hurry to get up the steam, every hatchway 
in the engine-room should be opened, that the fires may 
get a good supply of air, in order that the oxygen may 
combine freely with the combustible. The time taken in 
getting up the steam will vary with the moisture of the 
air and the force of the wind. 

199. Duties to various parts of the Engine, etc., while the 
Steam is getting up. 

1. Safety-valve. — It is a common practice to leave 
the safety-valves open after the fires are lighted : this is 
not a good plan. The object of doing so evidently is, to 
allow the air to escape that had been mechanically mixed 
with the water, and is liberated by the heating process. 
As this air becomes disengaged, its pressure acts on the 
surface of the water, and checks ebullition. Hence the 
safety-valves are commonly opened. But it is more judi- 
cious to let the heated air pass through the engines, where 
it will help to warm them. 

It is, however, possible that when the steam-pipe is of 
great length, time might be saved by keeping the commu- 
nication-valve closed until the steam is up, as a great deal 
of steam will be condensed in this pipe and in the jacket. 



166 GETTING UP THE STEAM. 

A loss from this cause must ensue whenever the starts 
ing of the steamer is delayed after the steam begins to 
form beyond the time necessary to heat the steam-pipe, 
jacket, etc., and the effects will depend on the amount of 
radiating surface. In a steamer in which the boiler was 
at a great distance from the cylinder, it was found that 
eight or ten minutes was saved by keeping the communi- 
cation-valve closed until the steam was up sufficiently 
to start. It would be well to try in each steamer which 
method ought to be adopted for the sake of saving time. 

2. Throttle-valve. — The throttle-valves should be 
opened shortly after the fires are lighted, to prevent their 
setting fast, which they will do, if kept shut ; for the steam 
and heated air will expand the valve ; and when set fast 
in its place, it will be impossible to get the steam into the 
cylinder. Cases of this kind have at times happened. 
Indeed, in one instance the engineer, whilst endeavoring 
to open the valve, was obliged to use such force that the 
lever broke off, and effectually prevented the ship from 
proceeding for some time. 

8. Lubricators. — The lubricators are generally trim- 
med and filled up before starting; because it cannot be 
so well done afterwards : it is true, it must still be done 
afterwards when under way ; but as this cannot be pre- 
vented, the waste consequent upon so doing must be borne 
with, and must not obviate the rule of carefully seizing 
the opportunity while stationary. 

4. The Moving Parts of th;e Engine. — Great care 
should be taken to ascertain whether any thing will in- 
terfere with the free working of the engine, particularly 
where it comes near some fixed part of the ship ; as, for 
example, while repairing the engine, blocks of wood are * 
interposed to support some of the heavy portions; and 
these are frequently left afterwards, and become a cause 
of serious mischief Where the cylinder-covers are re- 
cessed to admit of the piston cross-head working into 
them, so as to give greater length to the connecting-rod, 



I 



DUTIES TO ENGINES. 167 

these hollow spaces must be carefully cleared. In cold 
climates ice may have formed above and below the air- 
pump buckets, under the feed and bilge pumps, and all 
this requires consideration and care. When starting the 
engines, and hence, as we shall hereafter observe, when 
the use of the engines is no longer required (at least for a 
time), in cold climates the engines should be well blown 
through to get rid of all the water from them. If there 
be water above the bucket which cannot be got rid of by 
blowing through, the engines should be moved round as 
slowly as possible to drive the water into the hot- well. 

5. Funnel-Stays. — While getting up the steam, atten- 
tion should be paid to the funnel-stays. It is a practice 
in some steam-ships to tighten up the funnel-stays for the 
sake of appearances : they become slack after the steam 
has escaped, and the boiler cools down, because all the 
heated parts, such as boiler, uptake, funnel, etc., contract 
as they cool ; and the crown of the boiler, which had been 
in all likelihood somewhat forced up by the steam, recov- 
ers its shape. We must, therefore, when the fires have 
been lighted, take the precaution of slacking oif the fun- 
nel-stays till the steam is up, when they may be tightened 
again. Now it will generally happen, that, if the funnel 
be taunt, and the stays not too much spread, they will 
require a second setting up; and it is for the following 
reason : After the steam has been up some time, the heat 
from the funnel communicates with the stays, being con- 
ducted down them, so that they become lengthened, and 
slack again. If the ^ stays are much spread, the heat is 
carried off while endeavoring to ascend vertically, and 
consequently the stay does not expand so much. If no 
attention is paid to the stays, to slack them off as the top 
of the boiler rises, and the expansion goes on, either the 
stay or its fastenings will yield^. It is a common thing to 
see funnels, when much decayed, crippled {i.e. bulged out 
in places) ; this doubtless is owing to the stays being too 
taunt, as the funnel expands when raising the steam. In 



168 GETTING UP THE STEAM. 

one instance, the hoop round the funnel to which the 
stays were attached gave way, and nearly proved fatal to 
those who were walking on the deck at the time. The 
bolts in the gunwale have occasionally been drawn, when 
in a heavy sea, by the want of spread in the stays. The 
foremost stays are most affected in this way ; for, as the 
ship pitches, the funnel has a tendency to fall aft. To 
remedy this, the eye-bolts should be driven in at right 
angles to the direction of the strain. The plan has been 
adopted in some steamers, and effectually prevented the 
drawing out of the bolts. Whilst speaking of funnel-stays, 
we may observe that it is usual, where the funnel is taunt, 
in gales of wind to put up extra stays, midway between 
the deck and the other stays. These are sometimes called 
belly-stays, but more properly preventer-stays. They are 
particularly useful in despatch vessels, where the stays 
have not much spread. 

200. Injection-Orifice GhoTced up. 
On getting under way, it will at times be found that 
the injection-orifice is choked up. This is to be expected, 
in iron steamers especially, from the rapidity with which 
seaweed grows on iron when long stationary in salt-water. 
It will also be the case with copper-bottomed vessels after 
lying at anchor for any considerable time, unless the cop- 
per wastes quickly ; but more particularly if it happen in 
the spring of the year ; for seaweed, like all other vege- 
tation, is found to grow most rapidly at that season. To 
clear this, whenever it takes place, let the snifting-valve be 
secured down, and the valve in the waste- water pipe closed 
also ; then open the injection-cock and blow-through valve, 
and blow the engine through ; the steam not escaping by 
the snifting-valve, nor by the more tortuous passage 
through the air-pump and waste-pipe, will exert a- pressure 
on the seaweed at the mouth of the injection-pipe, and in 
all probability will force a passage. Mud will at times 
block ^up the orifices, particularly when they are low down, 



CHOKED UP. 169 

and tlie ship has been put ashore, or has taken the ground ; 
this may be cleared in the same way. It may be objected, 
that; since the injection-orifice is very low down, the steam 
will not have sufficient force to produce any good effect 
against the pressure of water on the outside ; but this can 
scarcely be the case with our present steamers, for very 
few have their steam-pressure less than 8 lbs. above that 
of the atmosphere ; and if we consider every two feet of 
water to produce one lb. pressure, the steam will have some 
effect if the depth is any thing less than 16 feet. If the 
pressure be 10 lbs. the depth may be increased to 20, and 
so on. The effective pressure will, however, manifestly be ^, 
less as the depth is greater.* In block-ships there may 
be some difficulty from the great draught of water, and 
because the injection sea-cock is so near the vessel's keel. 
The same method may be adopted to clear the orifice if 
choked up with ice. A vessel in the Thames was trying 
to force her way through a floe of ice ; and when just in 
the midst of it, she stopped for want of water to condense 
the steam ; for in those days the steam-pressure was so low 
in the boiler that the engines could not be worked without 
injection- water. The steam, however, was blown through 
the pipe, and it thawed the ice so as to admit thfe water 
again. The vessel was but a small one, and consequently 
the orifice not far below the surface, and the steam-pres- 
sure in the boiler overcame the column of water. There 
may be some difficulty at times in discovering whether the 
orifice is cleared ; for the steam in the injection- j5ipe will 

* Let p = the pressure in the boiler, 

(X = depth of injection-cock below the surface of the water ; 
.*. since 34 feet of water give a pressure equal to that of the atmos- 
phere, or 14*75 lbs. per square inch ; 

34 : 14-75 : : a : •434a nearly. 
Multiply, therefore, the depth by -434, and we shall have the pres- 
sure of the water opposing the steam. 
Hence the available pressure is p — •434a. 

Moreover, ifa= -r-^— the force will be zero. 
•434 



170 GETTING UP THE STEAM. 

prevent tlie injection- water from entering, and we shall 
therefore be led to suppose the orifice is still choked np. 
If, however, there be any suspicion of this, shut the blow- 
valve, and apply the hand to the outside of the pipe ; and 
if it be found that the pipe is cold near the ship's side, and 
as we pass the hand along we suddenly arrive at a part 
where the steam still keeps the pipe hot, we may be cer- 
tain that the water and steam are struggling for the mastery, 
and that eventually the water will make its way. Its pro- 
gress will be expedited by the application of cold water 
to the outside of the pipe and condenser. 

► 201. Danger to the Engine from Solid Bodies under the 
moving parts. 
In frosty weather the water in some parts of the engine 
may become frozen, and be the source of danger to the 
engine, particularly under the plungers of the feed and 
bilge pumps. If not moved before the pumps are set in 
operation, the stroke of the plungers may knock out the 
bottoms of the pumps. In the case of the feed-pump, the 
ice may be removed by blowing through, if the waste- 
water pipe and snifting-valve be previously closed. In 
case of the bilge-pump, heat must be applied externally. 
Ice is apt to form also in the air-pump, and may be thawed 
by blowing through. If the vessel take the ground, great 
difficulty is frequently experienced from sand and dirt 
getting into the engines. Sand, for instance, will accumu- 
late under the air-pump bucket, and prevent the complete 
downward stroke; the engine in this case must break 
down. When a steamer is on shore with a sandy or muddy 
bottom, it is well not to work the engines too long with a 
view to start her, for all propellers stir up the sand, etc. 
If a ship do not start with the first few turns of the engines 
there is not much chance of their effecting it. 

202. The Snifting-valve " drawing Air^ 
On first getting up the steam, and attempting to get a 



OBSTRUCTIONS. 171 

vacTiTim in tlie condenser, it is sometimes found that tlie 
snifting-valve is "drawing air," as it is termed; that is to 
say, from the valve not fitting tight, air is making its way 
by these means into the condenser. This is liable to 
happen from a piece of chip or coal, or a piece of seaweed, 
having passed into the condenser, and becoming jammed 
under the valve, which allows air to pass in and destroy 
the vacuum under the air-pump bucket. It is usually re- 
medied by a bucket of water being poured on the valve. 
If this be repeated two or three times, it will generally 
clear it. Sometimes a piece of oakum will get under the 
valve, which is generally the source of great trouble ; for 
it is apt to wind itself round the spindle, and the water^ 
will not be able to wash it away. The consequences of 
air getting into the engine through the snifting-valve have 
proved to be more serious than could at first sight be im- 
agined. The snifting-valve not being closed, we shall in , 
many engines have a pressure of air against one side of the 
foot- valve; and the injection- water producing a vacuum 
in the condenser, that valve will not open on the up-stroke 
of the air-pump, and the water not being pumped off will 
rapidly accumulate in the condenser, and at length find its 
way into the cylinder ; and consequently the engine wiU, 
in all probability, be broken down. Such an accumulated 
catastrophe, arising from so slight a cause, reminds one of 
the nursery- tale commencing with, "For want of a nail the 
shoe was lost," and terminating with the catastrophe of 
the rider being slain by the enemy ; and serves to show 
the value of much of our early legendary information, if 
we would but bring it to mind occasionally. For the case 
is by no means exaggerated, as the accident actually hap- 
pened to a steam-boat in Scotland some time since from a 
thread of seaweed getting under the snifting-valve. 

203. The Foot-valve gagged, owing to the Engine having he- 
come hot. 

The foot-valve may become gagged from the following 



172 GETTING UP THE STEAM. 

cause. Should the engine have become hot owing to ex- 
cessive blowing-through, leaky slides, leaky blow-valve, 
etc., and too much injection- water be admitted while the 
whole engine is hot in consequence of the steam, the water 
will have the effect of condensing the steam in the con- 
denser, but not in the air-pump, and the result may be the 
same as in the last article. In some old engines a cock 
was fitted to the condenser to admit air and equalize the 
pressure, if needful, in the condenser and air-pump ; but 
since escape- valves have been fitted to the cylinder this 
cock has been dispensed with. 

204. Starting the Engines. 
The first thing to be done is to ascertain with what kind 
of slide the engines are fitted ; if with the long D-slide, it 
must be raised to admit steam ahove the piston, and de- 
pressed to admit the steam helow the piston ; but if with 
the locomotive slide or Seaward's slides, the reverse must 
take place. Having ascertained this, we may look at the 
slide to see how it is worked by means of the starting- 
gear.* Let this gear be so moved as to give the necessary 
motion of the piston, and consequently to the crank. This 
part of the manipulation requires some careful considera- 
tion ; and each engineer must lay down a technical rule 
for himself on which he can act without hesitation when 
he receives his orders, because there is then no time for 
reflection. The best rule, generally speaking, is to leave 
the piston and slide out of consideration, and notice 
whether the motion of the starting-gear in one direction 
will produce a motion of the cranh in the same, or in the 
opposite, direction. The engines should be worked a few 
turns by hand, in nearly all cases, before being thrown into 
gear, to let the steam act on the piston throughout the stroTce, 
which it will not do when the slide is worked by the eccen- 

* In Plate II. the leng horizontal lever connected with the gab- 
lever is called the starting-bar, because it is the lever by which the 
slide is moved by hand. 



WORKING THE ENGINES. 173 

trie, on account of tlie lap. When working by hand, any 
water that may happen to be in the cylinder will be at lib- 
erty to escape through the ports. When the slide is moved 
to admit steam to the piston, the injection- cock should be 
open to admit water to the condensers, otherwise the en- 
gines will move sluggishly. Some engines will not start 
unless the injection-cock be opened. In starting an engine, 
it is a good plan to commence the motion with the throttle- 
valve only partially open, and increase the supply of steam 
and injection as the ship gathers way : in most cases, the 
injection should be supplied very gradually, or the water 
will be liable to get into the cylinders, and the work 
thrown on the air-pump will be too much while the engine 
is moving but slowly. 

205. Starting with one Engine in Gear. 
In case the engines are fitted with single eccentrics, this 
may be done when there is a scarcity of hands in the en- 
gine-room. One engine must have been thrawn out of 
gear at the time the slide of the other was at half-stroke, 
and therefore both ports were closed. If in this position 
the engine not in gear be worked by hand, steam will im- 
mediately be admitted to the other engine, because the 
slide is on the point of opening to steam. This plan can 
only be adopted when continuing to go the same way. To 
reverse the engine, both engines must evidently be thrown 
out of gear. 

206. Working the Engine at the Moorings. 
When the steam is nearly up, it is a common and very 
useful rule to work the engines by hand a turn or two 
before starting, to see that all is right ; and it is well to 
throw them into gear (if fitted with single eccentrics), to 
see whether the eccentrics are at liberty to slip round on 
the shaft ; for at times they set fast, and perhaps it may be 
midway between the stops for the head and sternway ; so 
that on being thrown into gear the engine stops, for the 



174 GETTING UP THE STEAM. 

ports to the cylinder are not opened at the proper time * 
If we refer to the article on Setting the Slides, we shall see 
that the stops are placed on the eccentric so as to admit 
the steam at a particular part of the stroke, that is to say, 
near the end ; but if the eccentric become fixed on the 
shaft from any cause, it evidently comes to the same thing 
as if the stops had originally been put on wrong, and the 
steam were therefore admitted at an improper time. Water 
dropping into the engine-room from leaky hatchways will 
tend to cause the eccentric to rust on the shaft ; or if the 
bearings get hot, and it becomes necessary to use water 
to cool them, the oil will be washed off from all the parts 
in the neighborhood of the bearing. The eccentric will 
sometimes not work freely for another reason. The brass 
ring of the eccentric is at times tightened up while in har- 
bor ; and by so doing it may become fixed, so as not to 
allow the gab to fall on to the pin, the rod remaining sus- 
pended on account of the friction. This defect can in most 
cases be remedied while the engine is being worked by 
hand. 

207. Whether a Steam-ship may start before the Steam is 
well up. 

This will depend on the anchorage of the steamer. If 
she have to go for any distance where no accident could 
happen provided the steam became low in the boiler — as 
for instance, in an open roadstead, or a harbor not crowded 
— then there would be no necessity for waiting till the 
steam has reached its full pressure. Thus if the full steam 
were 8 or 10 lbs., it is not necessary to wait till it blows 
off*; as soon as the guage has risen 2 or 3 inches, the pro- 
cess of blowing-through might be effected ; and as soon as 
the boiler has recovered from this, the vessel may be con- 
sidered ready to start, on condition that she gets up the 
steam to its full pressure as she proceeds. Of course, if 
no after -precautions be observed, since the demand is 

* This refers to engines fitted with single eccentrics. 



EEMEDIES AGAINST PEIMING. 177 

the fact, that fresh water boils at a lower temperature than 
salt water, and therefore, as the fresh water enters the 
boiler previously heated, the ebullition is more violent : 
but the contrary case is difficult to explain ; and, indeed, 
Jthis latter instance would almost lead one to suppose the 
former explanation not to be the true one. The same diffi- 
culty occurs in attempting remedies for priming; for 
melted tallow on the surface of some boilers will check 
the priming, and in others it will increase it. 

We will not enter here into one of the principal causes 
of priming, namely, the form and dimensions of the boiler 
and steam-chest, because that is a matter beyond the con- 
trol of the engineer and officers of the ship ; but it is very 
clear, that if a larger steam space were allowed, and com- 
bustion took place more slowly, and the boilers were not 
so contracted at the water-surface as many of our marine 
boilers are, we should not hear so much of priming. It is 
probably true, that those who have the management of the 
Cornish engines scarcely know the meaning of the phrase. 

211. Priming while getting up the Steam. 
If the boiler prime while getting up the steam, as may 
happen if it be filled with fresh water, the dampers should 
be shut, the fires put back, and, at the same time, an extra 
quantity of water should be thrown in by the hand-pump 
or the auxiliary engine ; by thus checking the ebullition, 
the priming will probably cease. If the boiler be liable 
to prime, the stop -valves should be carefully closed, to 
prevent water from getting into the engines by the sudden 
ebullition, and only partially opened on first starting. 

212. Remedies against Priming. 
The remedy usually adopted to prevent priming is the 
introduction of tallow. Some boilers have a syringe fitted 
on purpose ; others have a stop-cock attached to the feed- 
pump, so as to charge it for one stroke with tallow. The 
auxiliary engine, if fitted, may also be employed to force 



178 GETTING UP THE STEAM. 

tallow into the boiler. If the steam-pressure be reduced, 
it may be introduced through the reverse-valve or through 
the glass water-gauge. 

Priming has been successfully got rid of in some vessels 
by placing two flat pieces of perforated iron near the steam- 
pipe, taking care that the perforations of the two plates 
are not in the line of the pipe. Any water that gets 
through the perforations of the first plate will impinge on 
the solid portion of the second and be stopped. It will 
also be reduced by increasing the size of the steam-chest. 
If a steam-dome be added for this purpose, it is right not 
to cut the piece entirely out of the boiler, but to perforate 
it, that it may serve as a strainer of the steam. 

213. On the Effect produced on Fires hy Cold Surfaces. 

If the water in a boiler be cold, there are two distinct 
causes for delay in getting up the steam. The first is be- 
cause time will be lost in warming the water ; the second 
is, that the flame will not burn so briskly when coming in 
contact with cold iron as it would do if it were hotter, 
This may be proved experimentally by any one who is de- 
sirous of putting it to the test : let him take a very small 
cotton- wick, and float it in oil ; after applying a light to it, 
let him bring down a ring of cold metal, so as to surround 
the flame, and it will shortly be extinguished. 
214. On Banking up the Fires. 

Banking up the fires is an economical measure. It is 
practised whenever circumstances require that the engine 
should be stopped and started again after a short notice 
given, such as twenty minutes or half an hour, for prepara- 
tion. If the service on which the vessel be employed ad 
mit of a delay of from one hour to an hour and a half 
after orders are received to start, economy may generally 
be effected by putting the fires out and retaining the water 
in the boilers (allowing it to cool down),* and closing the 
communication- valves. 

* This has been clearly established by some experiments of Lieu- 
tenant Halkett's. 



PUTTING THE FIRES BACK. 179 

The operation of banking np may be described as fol- 
lows : the fires are put back against tbe bridge ; small wet 
coals and asbes are thrown on them, and the dampers 
closed ; if dampers are not fitted, or if tbey do not fit tight, 
the ash-pit doors are closed. -. " Banking np" has been prac- 
tised on the following occasions : for instance, after anchor- 
ing, when it is probable the vessel will have to get under 
way in the course of a short time ; or if, owing to a gale 
of wind or a strong tide, it is expected that it may be ne- 
cessary to use the steam for easing the strain on the cables. 
In these cases the steam may be allowed to fall to atmos- 
pheric pressure, if it be known that it will not be required 
till after suf&cient notice. If, however, the vessel be an- 
chored in a roadstead, it may be necessary to have the 
steam in such readiness as to be able to blow through and 
move ahead at very short notice. In this case the pressure 
must be kept higher. When banking up under sail, the 
pressure at which the steam is retained is determined by 
the nature of the service and the strength and variableness 
of the wind. If the steam has been allowed to fall to at- 
mospheric pressure, from twenty to thirty minutes will be 
required to get it up. This will depend on the nature of 
the coal (Welsh coal requiring more time than north- 
country coal). The temperature to which the boiler is 
cooled in a given time will have an effect on the time to 
heat it again, as also will the temperature and humidity of 
the air. 

215. Putting the Fires hack. 
If an order be given to stop for a few minutes only, the 
dampers or ash-pits are to be closed, and the fires are only 
put back so as to diminish for the time the consumption 
of fuel and production of steam. As the engine must- be 
ready to start the instant the order is given, the steam is 
not allowed to fall below the maximum pressure. Where 
tubular boilers are fitted, simply opening the lower part of 



180 GETTING UP THE STEAM. 

the smoke-box doors is sufficient to check the production 
of steam. 

216. The Safety-valves with Fires tanked up. 
It is a custom in some cases, when the fires are banked 
up, to keep the safety-valves open, their object being not 
to tax the boiler when it is unnecessary to do so ; but the 
prudence of such a plan is much to be questioned, for we 
may be injuring the boiler in another way, namely, by the 
saturation of the water. For as long as the safety-valve 
remains open, steam will be escaping, and the water in the 
boiler will become highly saturated, so that it becomes 
necessary, after a time, to displace a certain quantity of 
the brine by blowing off. ISTow this will certainly be un- 
necessary if the safety-valve be kept closed, for the danger 
from closing it is not to be mentioned, since it will always 
be possible to keep the steam below the point at which it 
escapes. Let, therefore, the safety and communication 
valves be closed, and endeavor by these means to keep all 
the steam in the boiler : we shall be able to effect this, 
provided the heat of the fires, when banked up, is only 
sufficient to counteract the loss attendant on radiation. 
The steam will, when generated, condense on the inner sur- 
face of the boiler, and trickling down its sides, will fall 
again into the water, to be reconverted into steam, and un- 
dergo a repetition of the process. If this can be managed, 
it will be quite unnecessary to blow out. • 

217. Steam-gauges of a strange VesseVs Boilers. 
On first getting up the steam in strange boilers, the steam- 
gauges shoilld be carefully examined when the fires are 
lighted, to see if the floats be resting on the mercury. The 
following device has been adopted at times for the purpose 
of making the steam-pressure seem less than it actually is, 
and to make it appear that the engine is doing a great 
amount of work with weak steam. Two or three inches 
are cut off the steam-gauge float, and a cork or plate, with 



THROTTLE-VALVES. 181 

a hole in it, is inserted in the gauge-tube, so that the ball 
of the float rests on this, and the float does not come into 
contact with the mercury till the latter has risen up to it ; 
and as the rod is raised above its proper level, it will then 
appear to stand at zero, when the actual pressure is 2 or 
8 lbs. ; and whatever be the pressure indicated, the actual 
pressure will be 2 or 3 lbs. more. It is necessary, there- 
fore, to attend to this point on first taking charge of a fresh 
steamer. 

218. Attention to he paid to the Jackets, if the Engines befitted 

with them. 
If the cylinders be surrounded with jackets, and the com- 
munication-valve left open, they should be emptied as the 
steam is getting up, or the water remaining in them will 
condense some of the steam as it enters. Indeed, the jacket- 
cock should be always left a little open while under steam, 
for the same reason ; and also because the attention of the 
engineer may be called off, and he may thus forget that it 
is shut, when the condensed steam will collect as water in 
the jacket, will fill it, and eventually, if unnoticed, enter 
the slide-casing, and from thence pass to the cylinders. 

219. To ascertain on hoard a strange Steamer if the Throttle- 

valve or Blow-out Cocks be open or shut. 
On taking charge of a strange engine-room, it is some- 
times difficult to ascertain whether the throttle-valve be 
open or shut, because there may be no marks by which to 
discover it. We have already shown how necessary it is 
to have the throttle- valve at least partially open while get- 
ting up the steam (see p. 166). The following plan may 
be adopted : Move the lever, or whatever^ means are sup- 
plied for opening and shutting the valve, to its fullest ex- 
tent both ways, then let it be placed midway between these 
two extremes. Now since when at one extreme it will be 
quite closed, and at the other quite open, when placed half 
way it will be partially open. This is all we want till the 



182 GETTING UP THE STEAM. 

engine starts, for it will prevent any of the afore-mentioned 
casualties to the throttle^valve. Again, when the steam 
is up, open the blow- valve, and move the throttle-valve 
spindle to one extreme. Notice whether, by so doing, the 
passage of the steam is obstructed ; if so, the valve is closed, 
and the place of the spindle should be marked "shut;" but 
if not, it should be marked " open," and the other extreme 
marked accordingly. 

The same method may be pursued with blow-out cocks, 
if there are no distinguishing marks on them to show when 
they are open or when shut : the water passing in or out 
of t];ie boiler would indicate when they are open and when 
shut. 

We may ascertain whether the expansion- valve be open 
or shut, by inspection of the cam at the shaft : if the roller 
be on the shaft, it is closed ; if on the cam, it is open. 



CHAPTER YI. 

DUTIES TO MACHINERY WHEN UNDIE STEAM. 

220. The Boiler, 

The boiler requires tlie constant attention of the engi- 
neer, because it is tbe source of power ; and not only so, 
but, being urged by beat, is more likely to become de- 
ranged, when neglected, tban any otber part of the machine. 

Accidents are sure to occur if the water be allowed to 
get low ; and therefore we readily infer that tubular boilers, 
having less water-surface, are a subject of greater anxiety 
than flue-boilers, that are not so contracted. As was pre- 
viously stated, the glass water-gauge shows us the water- 
level, and therefore the engineer's eye is continually ugon it ; 
the gauge-cocks also are occasionally tried, for fear the glass 
gauge should be choked, and fail to show the water-level, 
as also to keep them from choking up. 

221. On the choking up of the Glass Water-gauge, 
This is most likely to happen when the boiler is filled 
with muddy water. Let us suppose that from this cause 
the upper orifice chokes up, while the lower one is clear ; 
then the steam which is in the upper part of the glass will 
condense (partially at least), from the cooling effect of the 
atmosphere, and consequently the water will rise higher in 
the gauge than in the boiler ; indeed, the gauge will be 
nearly full, although it, may happen that the water is only 
just above the lower orifice within the boiler, and low 
enough perhaps to subject part of the upper tier of tubes, 
or the top of the flues, to the action of the fire. Again, 

183 



184 DUTIES TO MACHIISrERy WHEN UNDER STEAM. 

if we suppose both, orifices to liave become cboked, or tlie 
lower one only, the water-level in tbe gauge will not alter, 
however mucb it may vary in tbe boiler ; so tbat it wiU be 
of no use in indicating tbe quantity of water in tbe boiler. 
In explaining the construction of tbe glass water-gauge 
(see p. 67), it was said to be generally constructed in such 
a manner as to allow steam to be blown through it occa- 
sionally, to clear away any mud that may accumulate. 

222. On '' Blowing out while und^r Steams 

Blowing out should be strictly attended to while under 
steam at sea, to keep the boiler free from salt and incrusta- 
tion. The common practice has been to displace 5 or 6 
inches every hour; but as the necessary number of inches 
must depend on the capacity of the boiler and the degree 
of saturation at which it is determined to keep the boiler, 
the table D in Appendix should be consulted. If brine- 
pumps are properly proportioned, blowing out will evi- 
dently not be necessary ; but let not the blow-out cocks be 
neglected altogether, for they then act as a reserve in case 
the brine-pumps fail ; and if not attended to for some time, 
they will probably be found inefficient when wanted. Let 
them, therefore, be opened once a day at least, to keep them 
clear and in good working condition. 

When water which contains solid substances in solution 
is evaporated, these are. left behind, and therefore increase 
the state of saturation of the water remaining in the vessel, 
till the limit of saturation is reached. If pure water equal 
in amount to that which has been evaporated be now added, 
the ratio of the saturation will return to the same state as 
before the evaporation commenced. 

If we are unable to obtain pure water, yet if the water 
that is available have a less degree of saturation than that 
in the vessel before evaporation commenced, we shall be 
enabled to recover the original state of the fluid ; but it 



BLOWING OUT. 185 

will be necessary to throw in a larger amount of water 
than that evaporated. 

The water thus introduced is the feed- water, and it is 
clear that its aniount must depend on its own amount of 
saturation, the amount of water that has been evaporated, 
and the state of saturation at which we wish to keep the 
fluid. 

It has been stated that more feed- water, if not pure, must 
be thrown in than that evaporated; therefore the vessel 
containing it would continually get fuller. To avoid this, 
a certain portion must be got rid of; this quantity is what 
is " blown out" of a marine boiler at certain intervals. 

Hence the amount of feed- water to a boiler is equal to 
the amount evaporated and the amount '' blown out."* 

Table J) has been formed with the view of showing the 
ratio of feed, and amount blown out, to the evaporation, at 
the various degrees of saturation between that of sea- water 
and the highest point ; and likewise the probable loss of 
coal attending the process. This latter column has been 
determined as follows : Let us take the degree of satura- 
tion ^% ; the coal, if used beneficially, must raise the tem- 
perature from 100° to 1212^ that is, 1112° ; and if blown 
out, the temperature of that loss is water at 243*5°, hence 
143*5° are lost, and their volumes are as 1 : J ; hence the 

* Let A = area of base of boiler, 

33 = number of inches blown out, 
y = number of inches evaporated, 
• x-\-y = amount introduced by feed in same time, 
a == degree of saturation of sea-water, 
b = degree of saturation at which boiler is to be kept, 
Aa{x-\-y) = Abx 

and x4-y = , ^ 

or {b — a)x = ay 

rr ^y 
X^=z 



186 DUTIES TO MACHINERY WHEN UNDER STEAM. 

amount of heat used : that lost as 1112 : 71*75, and the 
amount lost : the whole amount 

71-75 : 1112 + 71-75 
71-75 : 1183-75 
-0606:1 
or : : 6-06 : 100* 

The only practical way of determining whether the 
amount of feed at any given rate of the ship is suf&cient, is 
to let the evaporation go on for a certain time, within the 
limits of safety to the boiler, without feeding or blowing 
out, and notice the amount to which the water falls in the 
gauge-glass : call this m ; then setting on the feed, let the 
evaporation go on for the same time, and call the rise in. 



, mi ^ + ^ ^ 

the water n. Then == -. — . Compare this 

. m evaporation ^ 

with table D, and we shall see the corresponding amount 

of saturation at which the feed then supplied will keep the 

water. 

223. On the point of Saturation, or the limit which the Boiler 
should not exceed. 

It is necessary to have some tests by which the saltness 
of the water in the boiler may be ascertained ; for if the 
amount of brine expelled by blowing out be not equal to 
that supplied by the feed-pumps, it follows that saturation 
will proceed, although a certain amount may be regularly 
got rid o£ There are two methods of ascertaining the de- 
gree of saltness of the water, viz., either by the thermometer 
or the hydrometer. 

1. We have before noticed (Chapter I.) that the boiling- 
point of water is influenced by the amount of salts it holds 
in solution. The following table "will serve to show how 
far this is true with solutions of brine of various degrees 
of saturation. Common sea-water contains about s'^ of its 

* For a general investigation on this subject, see the Miscellaneous 
Chapter. 



DEGREE OF SATURATION. 



187 



volume of salt and earthy matter, and therefore stands im- 
mediately under fresh water ; in the next line the solution 
is supposed to contain 5? of its volume, or twice as much ; 
and so on, till we arrive at H, which is called a saturated 
solution ; after which the water can contain no more in a 
dissolved state. The proportion of solid matter should 
never exceed ^is, as incrustation commences shortly before 
that point; therefore 216° is considered to be the extreme 
limit of the boiling-point, although no salt will be precipi- 
tated till the boiling-point reaches 226°, as we have said 
above. 



)portioii 01 salt m ii 
parts of water . . 


'"jo 


Boiling point . 


. 212-0^ 


(( << 


^ 


11 


213-2 


<( << 


^\ 


ii 


214-4 


it ■ 11 


5% 


a 


215-5 


" " 


^S 


a 


216-6 


(( ii 


/^ 


ti 


217-9 


a a 


^ 


It 


219-0 


« u 


/^ 


ti 


220-2 


a a 


^ 


ti 


221-4 


n a 


i^F 


tt 


222-5 


ti ii 


i^ 


u 


223-7 


a « 


ih 


ti 


224-9 


ti ii 


H 


tt 


226-0 



Advantage, therefore, may be taken of this fact by draw- 
ing off a small c[uantity of water from the boiler, and 
boiling it in the engine-room. For this purpose it is con- 
venient to boil it in a long copper vessel deep enough to 
hold the thermometer ; and the water should be kept in a 
good state of ebullition while the height of the thermome- 
ter is observed.* The point at which the thermometer 
stands must be read off carefully ; and, indeed, to perform 
the experiment properly, a thermometer specially adapted 

* Care should also be taken to make use of a thermometer on 
which some dependence may be placed. To this end, let the ther- 
mometer be first placed in pure fresh water when boiling, and ob- 
serve whether the mercury stands at 212° when the weather-barome- 
ter stands at 30 inches 



188 DUTIES TO MACHINERY WHEN. UNDER STEAM. 

o this purpose should be supplied, graduated with extreme 
care at and near the boiling-point, such as those constructed 
for ascertaining the heights of mountains by similar means. 
2. We may also ascertain the degree of saturation by 
the hydrometer, of which we will first give a description. 
The hydrometer consists of a hollow ball of glass or metal, 
with another small weight, or glass bulb partly filled with 
mercury, below it, to give it stability, and to sink it to a 
given depth. From the upper part of the bulb there rises 
a slender stem, which is graduated ; and since the instru- 
ment will sink to different depths in fluids of different 
specific gravities, it follows that the hydrometer may be 
conveniently made use of to determine the specific gravity, 
and therefore the saltness, of water from the boiler. But 
there is one particular on which the efficiency of this in- 
strument depends ; and for want of paying sufficient atten- 
tion to this point it becomes frequently quite useless when 
placed in charge of. those who are not accustomed to minute 
accuracy in observations. It is very evident that the den- 
sity of the water depends on its temperature as wefl as on 
its saltness, and therefore the saturated solution of a high 
temperature will frequently be of less specific gravity than 
that which is not so highly saturated at a lower tempera- 
ture. To convince ourselves of the material change which 
takes place in the density of the water, let us place the hy- 
drometer in cold fresh water, and place the vessel contain- 
ing it on the fire : as the water becomes heated, it will 
gradually sink ; and if the experiment be made with one 
of those supplied to our steamers, it will sink altogether 
before the water boils. Therefore on the side of the stem 
opposite the graduations we find the number 55°, which 
expresses the temperature the water ought to have when 
the hydrometer is placed in it. Now the hydrometers at 
present used in the naval service are very inconvenient, 
unless they are differently constructed from those we have 
seen ; for this temperature 55° is considerably too low, for 
two reasons. In the first place, it would be impossible, 



DEGREE OF SAT^^URATION". 



189 



when on board a steamer in ivery hot countries^ to cool 
down the water so low as 55°ir; and in all cases it would 
be so long cooling down to tJthis temperature, after being 
drawn off from the boiler i^n a boiling state, that all ob- 
servations would necessariLy be very protracted. And 
secondly, there is no paper .s.accompanying the instrument, 
and giving an explanation o:^ its principles and the mean- 
ing of the graduations on thde stem. The mark W, how- 
ever, is evidently the point tor which the hydrometer should 
sink when floating in fresh iwater at 55° ; but beyond this 
we have no information. Fueling, in common with others, 
the want of something more \ definite to make the instru- 
ment practically useful, we hive made some observations, 
which will, it is hoped, be of c service. 



Boiling-point of 
water from the 
Jjoiler. 



2130 

214 

215 

216 

217 

218 



When the watij^er had 
cooled down tci 200°, 
the hydromete^T stood 
at 



W orO . 

6 " 

11 i 

351^ 



When it had cooled 
down to 64°, the hydrom- 
eter stood at 



12 
•20 
25 
30 
40 
51 



These results are not so regular as could be wished ; and 
if the experiments had b<^en continued over a longer tirne 
it would have been adf -ntageous. Any engineer, iiow^ 
ever, may make similar exp>eriments, and will probably be 
enabled to make the table more perfect, and at the same 
time gain great practical knowledge of the hydrometer 
The two points to be carefulfy attended to in all such ex- 
periments are, the height of t.^he weather-barometer and a 
full state of ebullition of the ws^iter when the thermometer 
is placed in it. In forming th^^ above table, the weather- 
barometer stood at 30 inches. 'Since the boiling-point of 
water from the boi"'er should ney&r exceed V.\^°, it follows 
that the hydrometer should alw^iys sink :xii the mark 16 



ISO DUTIES TO machinim:ry when under steam. 

comes to the level of the \ water wlien at 200°, or till tlie 
mark 80 comes to the surfac\ e at 64°. 

224. The S^'iUnometer, 
This name is given to a pecij'Juliar kind of boiler water- 
gauge; it contains within it a /hydrometer and thermome- 
ter; so that the temperature a/.nd density of the water can 
at all times be ascertained by/ inspection. 

\- 
225. Ash-pits not to he cholced ^p with Ashes, etc. — Results 
of throwing "^IWater there. 
Whatever kind of coal is uAsed in a steamer, it is a prac- 
tice to get the ashes out of / the ash-pit every four hours 
(the vessel being supposed tj o be going at full speed, and 
not burning the ashes). Bui t if large quantities of them 
are retained in the ash-pits, tj hey absorb the oxygen of the 
air, because they are necessariily yq^j hot, and consequently 
the supply to the fires is dimhnished. Besides which, they 
take up some of the space V within the ash-pits. They 
should, therefore, be hauled of ut frequently ; and when the 
boiler, from want of evaporative power, will not allow the 
ashes to be reburnt, let them (De heaped up between the 
fireplaces, and when they have\ accummulated in sufficient 
quantity, let them be thrown overboard. In some vessels 
a practice is adopted, which is Wuch to be reprehended^ 
viz., that of throwing water into\ the ash-pits, with a view 
to cool the ashes : this will, in 4 short time, destroy the 
bottom ; the water thrown in ^'evaporates, and the salt is 
left behind, which will rapidl}/ oxidate the plates. Boilers 
have been known to require i new ash-pit bottoms in the 
short spaoe of time of eightfien months, and the sides im- 
mediately" tibove the angle/iron required patching: this 
arose from the cause above/ mentioned. But it should be 
stated, that this happened jcen or twelve years ago, before 
engineers had gained their} present experience. Moreoveo-, 
stokers have, been scalded /fcoTn throwing water on the hot 
ashes, and gei. -"'^'T+vng t-tealm in the asr..-pit rapidly, which 



ON STOKING. 191 

not finding vent througli the fire-bars, comes into the en- 
gine-room, bringing with it impalpable ashes, that settle 
on the various parts of the engine, to be washed into the 
bearings the first time the parts are oiled. The ashes 
should be quenched on the stoke-hole plates, and it might 
be advisable to have buckets made on purpose, with half- 
rose tops ; the arms of the stoker would thus be saved, as 
steam would not be generated so fast, and the dust would 
not be so great. A watering-pot, such as is used in some 
men-of-war for laying the dust on the decks, would answer 
the purpose. The fire-bars are subject to rapid oxidation 
from wetting the ashes in the ash-pits ; the steam evolved 
from the ashes, acting upon them^ cools them, and the water 
becoming decomposed, scales of o'xide of iron come off, and 
the bars are deteriorated and weakened. 

226. On Stoking f^ 

The economy of the working of an engine depends very 
materially on the attention paid to the stoking. The state 
in which the fires should be kept to obtain the maximum 
effect varies slightly with different boilers and different 
kinds of coal. Fireplaces with great draught should have 
a thicker layer of coals on the bars than those of sluggish 
draught. 

Welsh coal does not adhere or stick together like north- 
country coal ; the former, not being bituminous, should be 
kept somewhat thicker than the latter. If anthracite coal 
be used by itself, the fires should be very thick. When 
Welsh and north-country coal are mixed, the usual thick- 
ness may be preserved. 

As a general rule, the fires should be kept thin towards 
the back, to allow air to get in at the back of the furnace ; 
and by so doing, create a greater rush of air through the 
ash-pits, which will more thoroughly ignite the gases. 

* The remarks on fuel in the Appendix, which are the results of 
researches by Sir H. De la Beche and Dr. Lyon Playfair, should be 
read before proceeding further. 
13 



192 DUTIES TO MACHINEKY WHEN" UNDER STEAM. 

"With Welsh coal, it will be found necessary to have the 
fire-bars wider apart than when using other kinds of fuel, 
so as to admit the air freely, 

227. Fires to he cleaned out occasionally. 
The fires should be cleaned out as they require it, that 
is to say, the clinkers* that form on the fire-bars should be 
removed ; for it; is easily seen, that a mass of the dross of 
the coal, settling itself on the 'fire-bars, must choke up the 
intervening spaces, and check the draught. The clinkers 
are to be removed as follows. The fires are allowed to 
burn down (to speak technically), then an instrument called 
a slice is pushed under the clinker, so as to raise it off the 
bars and detach it ; after this is done, the rake is made use 
of to haul it out. We may form some idea of the evil 
arising from allowing the clinkers to remain, when it is 
known that they are sometimes too large to come out of 
the fire-doors whole. Before hauling out the clinkers, the 
fires should be put back ; they are afterwards hauled for- 
ward again, and fresh coal laid upon them. 

After all the clinkers are out, it is as well to shut the 
door, and haul the ashes out of the ash-pit ; for when the 
fresh coal is thrown in, some small coal will fall through 
the bars and be wasted, if any ashes be there ; but if the 
pit have been previously cleared out, what falls through 
may be afterwards raked out and burned. 

Clearing the fire-bars will, as a matter of course, depress 
the steam for some time ; for the water will not only lose 
the effect of the fire, but the cold air entering at the open 
door will check the other fires. The amount of depression 
will depend on the evaporating power of the boiler and the 
smallness of the steam-chest. In a boiler that keeps its 
steam easily, and has a large steam-chest, the deficiency 
will not be felt ; for the supply will be tolerably well kept. 

* Clinkers are composed of the earthy matter, siUca, etc., of the 
coal, which, separated from it during combustion, and falling through 
the burning mass, runs down on the bars, to which they adhere. 



FEEDING BOILERS. 193 

up, and the quantity of steam previously in tlie steam-chest 
will act as a reservoir, from which the engine may fear- 
lessly draw for some time. 

228. On Feeding the Bdilers, 
In attending to 4;he feeding of the boilers, care must be 
taken that the water be not allowed to get either too high 
or too low. This is regulated by the feed-cocks or feed- 
valves. If the water be allowed to get too high, and so 
overfiaw the internal steam-pipe, it will make its way into 
the cylinder, and perhaps the engine will break down. 
Priming, again, is frequently caused by the water getting 
too high in the boilers, for in so doing we necessarily con- 
tract the steam-space. If the water be allowed to get too 
low, we shall be in danger of burning the flues or tubes of 
the boilers. The proper water-level is a matter of some 
nicety in many vessels ; some boilers keep steam better 
with the water well up than others. This takes place 
where there is a large uptake ; for if the passage from th^ 
fires to the uptake is very direct, the latter will be very 
hot, and will give out a considerable quantity of heat to 
the surrounding water. 

229. Method to he adopted in case the Blow-out CocTcs set fast, 

or Blow-out Pipes get stopped up with Scales, etc., and 

Brine-pumps are not fitted. 

When under steam, should the blow-out cocks set fast, 
so that they cannot be opened, and the vessel be not fitted 
with brine-pumps, or any other means of getting rid of the 
brine, it is evident the saltness of the water must rapidly 
increase. Some means must be taken to allow the water 
to escape from the boiler into the bilge, and thus make the 
bilge-pumps do the duty of brine-pumps. 

When the blow-out cocks set fast, and the brine-pumps 
do not act, it sometimes happens that the cocks of the boiler 
hand-pump or the auxiliary engine can be reversed ; and 
one of these can be used to pump water out of, instead of 



194 DUTIES TO MACHIXERY WHEN UNDER STEAM. 

into, tlie boiler. This plan was once adopted in the Ter- 
rible : the auxiliary engine was employed to extract the 
brine from the boiler. 

230. Steam hlowing off with violence when the Vessel is 
^pitching and rolling. ^ 

It must be borne in mind that the boiler of a marine 
engine is not under the same conditions as that of a land- 
engine. In the first place, the water-level is not preserved ; 
for the violent pitching and rolling of the ship produces 
its effect on the level of the water-surface. As the vessel 
pitches, the water rises violently at the fore part of the 
boiler, and acts on the steam, which is recumbent, as it 
were, upon its surface. So suddenly does this take place, 
that the steam is driven up against the safety-valve before 
it can make its way to the place the water has left, and the 
valve will be found to lift, and the steam makes its escape. 
Again, as the vessel pitches, or rolls, the safety-valve (if 
loaded by a weight) does not press with such force as it 
would if the boiler were upright : to find the effective pres- 
sure, we must multiply the nominal pressure by the cosine 
of the angle between the direction of the spindle and the 
vertical line. To see how this applies, we have only to 
take a very extreme case ; let, for instance, the ship be 
supposed on her beam-ends, so that the top of the boiler, 
instead of being horizontal, is vertical : it is plain that in 
such position the valve would not press on the seat at all, 
however highly it be loaded ; and if the boiler were made 
to revolve still further, the valve would actually tumble 
out. 

231. Blowing out to he limited when the Vessel is going slow. 
When head to wind, and sea, or towing (unless fitted 
with a second motion), or when working very expansively, 
it will not be necessary to blow out so much as when going 
at full speed ; for as we evaporate less water, there is less 
brine left behind. Of course it is here supposed that the 



NUMBER OF BOILERS TO BE USED. 195 

engineer does not allow the steam which would have gone 
into the engines, if thej had been going at full speed, to 
escape bj the waste- steam funnel. 

Again, it sometimes happens, either from the vessel hav- 
ing been supplied with bad coals, or some other cause, that 
the minimum quantity of water consistent with safety has 
been blown out for some time, for fear of diminishing the 
quantity of steam produced. We will therefore suppose 
the water to have become highly saturated. The engineer 
will then take advantage of the vessel going slower, or any 
other adverse circumstances, and get rid of as much of the 
saturated water as can possibly be spared. It must be 
borne in mind, however, that this case is an exception to 
the general rule, viz., that the amount of saturation de- 
pends on the ratio of the feed to the evaporation, and that 
the quantity blown out is merely the quantity that accu- 
mulates in the boiler by the exc^ess of feed 

232. Number of Boilers to he used when not at full speed. 

There is a common practice in our steam navy, when 
employed on a service in which particular despatch is not 
the object, to use half the number of boilers, and proceed 
at a speed proportionably less, in order to consume less 
fuel in traversing the distance. The saving thus effected 
depends on the fact, that the consumption of fuel per hour 
varies as the cube of the speed, and the consumption of 
fuel per mile depends on the square of the speed (see Mis- 
cellaneous Chapter). Suppose, for instance, a vessel to be 
furnished with four boilers, and that her speed when using 
all four is ten knots ; her speed with two boilers would be 
eight knots nearly. Let us suppose, for argument sake, 
each boiler consumed half a ton an hour ; then, at full 
speed, four half-tons, or two tons, would drive the ship over 
ten knots, or one ton would propel her over five knots. 
Again, in the second case, two half-tons, or one ton, would 
send her over eight knots. Hence we should by this 
method gain three knots in distance for every ton of coal : 



196 DUTIES TO MACHINERY WHEN UNDER STEAM. 

and we may set it down as a general maxim, that tlie slower 
a vessel goes, tlie greater the distance she will steam over 
with the same consumption of fuel. This is on the sup- 
position that she meets with no strong head- winds, etc., 
such as to force her to use all her power. If, however, 
the wind or tide would have the effect of making her go 
astern, her rate through the water for the greatest economy 
of fuel should be at least half as great again as she would 
have gone in the opposite direction if no power had been 
used. Thus if a vessel be steaming up a river which 
flows at the rate of four knots, her most economical speed* 
would not be less than six knots, making good two knots 
over the ground. 

But it is a question for mature consideration, whether a 
still further saving might not be effected by a different 
mode of managing the fires. Suppose, for instance, as we 
had at first arranged, that the vessel be going at eight knots, 
using two boilers instead of four. The alteration we would 
propose is, that instead of using two boilers she should use 
three or more ;* but that the speed of the ship should still 
not exceed eight knots, which she would have had with 
two boilers. To effect this, the engineer must do all he can 
to produce a slow combustion ; and it will be found that 
by this slow combustion a considerable saving will be 
effected. Those of our readers who are conversant with 
the mode of producing steam on the Cornish system will 
be more likely to appreciate this ; for our endeavor is to 
make the two methods approximate, by spreading the fuel 
over a greater number of tubes, and so allowing more sur- 

* In the Report of the trials made on the French screw ship-of- 
war Charlemagne, contained in the Artizan for September, 1853, we 
have the following fact corroborating the above remarks ; 

" The commission wished to assure themselves if any economy of 
fuel could be obtained by using three boilers, and maintaining the 
same number of revolutions. With this view a third boiler was 
lighted. The consumption of coal with the three boilers was 66,679 
lbs. per 24 hours, as against 73,558 lbs. with the two boilers, being a 
saving of 9-3 per cent." 



SUPEEHEATING. 197 

face to impart their heat to the water. The Cornish boiler, 
however, is not suitable for marine purposes, as^ owing to 
its peculiar construction, it would take up too much room, 
the amount of heating surface being much greater in pro- 
portion than the common boilers. This plan was tried for 
a short time on board H. M. S. Avenger, though not long 
enough to obtain any measured results. An order had 
been given to go on with two boilers, and the fires in them 
were worked in the usual way, and kept in an active state 
of combustion. Shortly afterwards the order was given 
to proceed with three boilers, but no additional orders 
were received to go on faster than with the two. It was 
then found to be scarcely possible to cover the fire-bars in 
all the boilers with fuel, the rapid absorption from the 
great quantity of surface was so effective in keeping up 
the steam, and the amount required being so small. The 
saving of fuel was very great ; but the limited time of the 
trial would not allow the actual quantity to be ascertained. 
If difficulties should arise, when using large boilers, in ob- 
taining a small supply of steam — that is to say, if it be 
found that, when all the fire-bars are covered, too much is 
generated — let one or more fires, in each boiler clinker up, 
and their ash-pit doors be closed. And in using the boilers 
in this way, the ashes may be repeatedly burned over 
again, merely throwing the clinkers away. 

In working expansively, it has generally been supposed 
that it is more economical to use as few of the boilers as 
possible. But if the boilers are in close contact, without 
any non-conducting substance between them, a great deal 
of heat will escape into the empty boiler : and in this case 
it will be found more economical to use all the boilers. 

233. Superheating Apparatus. 

The principle on which superheated steam is applied 

has been stated in the preliminary chapter, and very little 

remains to be done but to describe the process by which the 

waste heat ascending the funnel is utilized for this purpose. 



10 



DUTIES TO MACHINERY WHEN UNDER STEAM. 



In the accompanying diagram, let A A represent tlie upper 

I_,,,,_^_^^^_^ part of the boiler, B B 
H^^bB^^^BH ^^^ uptake, C G tubes 
^^^^^^■^^^|HH through which the steam 
|g^=gg!^= M M^B^B passes (the heated gases 
I ^ P F^^ HB ci^c^^^^^^g round them); 

I ^ bBBBBI ^1^2 two chambers or 

■HiHi^S^BlHl ^^^^^' ^^^> -^1' ^^^ ^^' 
^B^^HH^^QHB duction, and the other, 
^B^^HHBB^KS D2, the eduction; G 
H^^^HHbH|H| the main steam-pipe, in 
BBSSBSSsm^ttmmtJ which is a stop-valve, 
shown by a dotted line, to prevent, at will, the steam 
from passing to the engines the usual way ; bi h^ also two 
stop-valves, for the purpose of shutting off the super- 
heating apparatus if required. We have here shown the 
application of the above as fitted to one boiler. If more 
than one be fitted, an induction and eduction chamber 
must be brought from each boiler to the superheated 
chambers. The heating surface of the tubes is from two 
and a half to three square feet per horse-power. 

234. On Ashes and turning Coal escaping from the Funnel. 
Sometimes hot ashes and burning coal will be forced 
from the fires through the flues or tubes up the funnel, 
from which they will fall on the deck, and may set fire to 
the awnings. This can only arise from a defect in the 
construction of the boiler, and cannot be remedied, except 
perhaps by an alteration in the position of the fire-bridge. 
It does not follow that an alteration in the bridge, by short- 
ening the fireplace, will necessarily damage the steam-pro- 
ducing power of the boiler. Indeed, the opposite effect 
may be produced if done judiciously, when the transition 
from the fireplace to the flues is too abrupt and tortuous ; 
otherwise the damper must be partially closed, to let the 
fires burn less briskly, and check the draught. If, when 
the alteration has been made, the boiler do not keep its 



FLAME ISSUING FROM THE FUNNEL. 199 

steam, tlie expansive-gear or throttle-valve must be brought 
into use ; but if, on the other hand, great speed be our ob- 
ject, the primary evil will perhaps have to be put up with. 
However, it must be borne in mind that it may probably 
be checked by consenting to lose one or two revolutions 
of the engines, and this will not tell much upon the speed 
of the vessel, while a considerable saving of fuel will be 
effected ; for whenever we have to guard against the evil of 
ashes coming out of the funnel, Vyre may be sure that fuel 
is being wasted, and a great deal of heat expended on the 
funnel and lost in the atmosphere, instead of being ab- 
sorbed by the boilers. To prevent this, the boiler-tubes 
are sometimes ferruled at the smoke-box end. 

235. Flame o^ppearing to issue from the Funnel. 
In Chapter I. we stated that three things were, under 
ordinary circumstances, necessary for the combustion of 
fuel, viz., the combustible itself, the oxygen of the atmos- 
phere, and a sufficiently high temperature ; but if either 
or both of the latter be wanting, combustion will not take 
place. Now to apply this to the case in point, we readily 
see, that if a boiler is badly constructed, and a proper 
supply of air be not admitted to the furnaces, proper com- 
bustion cannot take place so long as the heated gases re- 
main in the funnel ; but directly they come in contact with 
the atmosphere, unless the temperature be too much re- 
duced, chemical union takes place, and flame is produced. 
Again, if fires be too thick on the bars, carbonic acid will 
be formed by the union of oxygen with the carbon which 
lies nearest to the bars, and the carbonic acid thus formed 
in passing through the upper strata of coals gets robbed 
by them of a portion of the oxygen, and is by this pro- 
cess converted into carbonic oxide, being thus reconverted 
into a combustible, which, if supplied with more oxygen, 
burns with a lambent bluish flame. Most persons must 
have noticed this on the top of a common fire that is be- 
ginning to burn clear ; and it is sometimes observable on 
the top of a steamer's funnel. - 



200 DUTIES TO MACHINEEY WHEN UNDER STEAM. 

236. On the Draught of Air to the Fires. 

Some vessels have difficulty in keeping up the steam, 
from a deficiency in the draught. From whatever cause 
this may arise — whether from some inherent defect in the 
boiler, or from a defect in the engine-room, whereby a free 
current*of air cannot make its way to the fires — it can be 
obviated, to a great extent, by fitting a small pipe with a 
stop- cock leading from the steam-chest into the funnel or 
uptake : the principle of this is the same as that of the 
blast-pipe opening into the funnel of a locomotive engine. 
The improved draught will more than make up for the 
loss of steam by which it is effected. The only objection 
to this appears to be that it oxidates the funnel, and the 
rust and soot are blown about the decks. 

The draught depends very much upon the state of the 
atmosphere ; the greater the elasticity of the atmosphere, 
the better the draught : and, in addition to this, the elastic 
pressure of the air on the safety-valve alters from day to 
day ; so that on a day in which the barometer stands high, 
the engine is working with stronger steam than on other 
days. 

237. What is necessary to he done when the Water is low in 
the Boiler. 

The water is apt to get low at times ; as, for instance, if 
the blow-out cock cannot be closed fast enough after blow- 
ing out. It is a bad plan in such cases to pump in water ; 
for if the fireplaces or tubes be red-hot, or nearly so, the 
consequences of injecting cold water would be the sudden 
production of steam in such quantity that the safety-valve 
would not allow it to pass off as fast as it is generated ; 
and even if an explosion did not take place, the iron of 
the boiler would be injured by the sudden cooling : this is 
likely to produce a crack in the boiler, or oxidate it, and 
so thin it down. Again, if allowed to remain hot, and no 
remedies be used, the pressure of the steam, acting on the 
crown of the heated fireplaces, will force them down : this 



INJECTION COCKS. 201 

will happen, even though some water be above the flues, 
unless there be enough to keep the lower particles in con- 
tact with the iron to carry off the heat ; to prevent which, 
the following remedy must be adopted. The fires must 
be pushed back, or hauled out, and. the boiler allowed to 
cool down of itself, the safety-valve being eased to get rid 
of the steam-pressure, as before ; but on no account should 
water be pumped in when there is any apprehension that 
the boiler has become over-heated. If, however, by any 
accident the water be low in the boiler, but not so low as 
to lay the tubes or flues bare, no time should be lost in 
opening all the feed, by putting on the second feed-pump, 
setting the auxiliary engine to work, opening the com- 
munication-pipes, easing the safety-valve to blow off some 
of the steam from the boiler, and relieve it of the pressure. 

238. On the depression of the Steam-pressure from admitting 
a great quantity of Water too suddenly. 
If we are obliged, as in the forementioned instance, to 
admit a great quantity of water, it must be expected that 
the steam will lose its elasticity, because it will not be pro- 
duced so rapidly for some time on account of the presence 
of the cold water. We shall, therefore, be under the 
necessity of throttling or working expansively till the 
boiler has recovered its energy, otherwise the engines will 
exhaust the boiler, and they will be brought to a stand- 
still. There is no danger to the engine, as some imagine, 
in working on a vacuum, as it is called : the only thing 
we have to dread is, that ihe engine will stop ; or that the 
boiler will collapse, if the reverse-valves are not in good 
working order. 

239. Attention to he paid to Injection-cocks. 
Where there is much fluctuation in the steam-pressure, 
and likewise if the speed of the engine be liable to vary, 
the injection-cock should be well attended to, else the en- 
gine may choke with too much water ; or, on the other 



202 DUTIES TO MACHINERY WHEN UNDER STEAM. 

hand, it may be working hot from having too little water. 
The best temperature of the condenser in these latitudes, 
and in vessels of light draught of water, is somewhat less 
than 100° Fah. ; but the temperature for the most economic 
working of the engine depends on three things, viz., the tem- 
perature of the injection-water ; the load on the pumps, or, 
in other words, the depth of the condenser below the surface of 
the sea; and lastly, the pressure of the steam on its exit from 
the cylinder to the condenser ; and if any of these quantities 
be increased, the necessary temperature of the condenser, 
and therefore the deficiency from the vacuum, will increase 
with it. Therefore in hot climates, where the sea is warmer, 
such as the coast of Africa, or the East or West Indies ; 
or, secondly, in our line-of-battle ships, where the waste 
water has to be forced out of the ships against a considera- 
ble pressure of the water outside ; or, lastly, if the engine 
have but little lap on the slide, so that the pressure of the 
steam at the end of the stroke is considerable — we shall, in 
any of these cases, have to increase the temperature of the 
condenser. The investigation connected with this subject 
will be given in the Miscellaneous Chapter. 

If the vessel be in a gale of wind, with a heavy sea, the 
injection- cock will require strict attention. "^ Here it would 
be better to work too hot than too cold, as being the lesser 
evil ; for when the engine is relieved of its load, as it will 
be at times in a sea-way, the quick motion will cause more 
steam to enter the condenser in a given time ; and if the 
injection-cock have been previously partially closed, the 
back pressure arising from the iijiperfect vacuum will pre- 
vent the engine from flying off so quickly. If, however, a 
good supply of water had been maintained, the engine 
would revolve too quickly at one time, and at another, 
when its motion was checked from the immersion of the 
wheels or the screw, there would have been too much water 
for the quantity of steam, and the engine would choke. In 
long voyages, where the consumption of fuel is an im- 
portant question, to work the engine rather warm will 



INJECTION-COCKS. 203 

conduce to a saving of fuel; and more especially where re-^ 
frigerators are not fitted for the purpose of warming the 
water that enters the boiler. 

Again, if we wish in hot climates to use the same quan- 
tity of injection- water as in the country where the engines 
were made, we may arrive, with tolerable accuracy, at the 
temperature the condenser must be kept at by adding 39° 
to the temperature of the injection water.* 

If the injection-cock is left open when stopped, the con- 
denser, will fill with water very rapidly ; and if the ports 

* When the temperature of the injection-water is higher than the 
manufacturer of the engine would naturally expect it to be, we may 
arrive at the temperature of the condenser, subject to the above con- 
dition, as follows : 

Let the temperature of the condenser be 100*^ when that of the in- 
jection-water is 60°. 

Then, by p. 33, 100 = ; — , 

l00w + 100w' = U12w-\-60w' ^ 
or 40 w' = 1112 w 

w' _ 1112 _ 139 

Let us now suppose the engine to have been originally constructed 

139 

so that the weight of injection-water is -— times the weight of 

& 

steam ; and therefore that if the proportion of injection-water be in- 
creased much above this, the engine will be overtaxed, owing to the 
extra work thrown on the air-pump. Hence we may assume the 
limiting value of this ratio to be 30. 

Again, let us assume that x is the temperature of condensation 
when t' is that of the injection-water. 
'w 
^ J 2l2 + -t' ^ 1212 + 30^^ 

''' ^— .. yy_ ^ 1+30 

w 

1212 + 30 i' 1212 , ,, , 
■+ 1 nearly. 



31 31 

= 39 + «' 
If, then, we add 39° to the temperature of the injection-water when 
high, we shall arrive, with tolerable exactness, at the temperature 
for the condenser. 



204 DUTIES TO MACHINERY WHEX UNDER STEAM. 

on the exhaust side are open, the cylinder also will fill : 
should this happen with only one engine, and the other be 
the starting-engine, an accident is very likely to occur, for 
it is not probable that the escape-valves will be able to 
relieve the cylinder of the water in time to enable the 
cranks to turn their centres. Cylinder-covers have been 
broken, and condensers burst, by these means. 

K the injection-cock or air-pump be leaky, the engine 
must be blown through at intervals when stationary, other- 
wise the water will gradually fill up the condenser, and the 
steam will not be able to start the piston. But the blow- 
ing through must be conducted with some judgment ; for 
if the condenser be made very hot by so doing, the evil 
from the want of vacuum will be nearly as great as that 
from too much water : indeed, the condenser may be made 
so hot, that the entering water will be for some time quite 
repulsed. When injection-cocks are very leaky, the sea- 
cocks should be pnly partially opened when the engine is 
stopped and started at intervals, having some one stationed 
to open them when the order is given to start, and close 
them again when the order is given to stop. 

Injection-pipes are mostly unconnected ; that is to say, 
a pipe from each sea-cock passes to one condenser only ; 
but many of the old engines had a pipe across the ship from 
one sea-cock to the other, and pipes from this went to each 
condenser. 

This plan had the advantage over the present, that if 
one sea-cock failed, or became stopped with sea- weed, ice, 
etc., both engines might still be worked. 

240. Kingston's Valves. 
When Kingston's valves are fitted to the sea-cocks, they 
should be kept open — unless when their working order is 
being tested — or they may, by the sudden opening of the 
injection-cock, clo^e, owing to the rush of water on the 
outside of the valve. This happened to a vessel, and it was 



INJECTING FROM THE BILGE. ■ 205 

some time before tlie reason why there was no injection- 
water was discovered. 

Kingston's valves are very apt to set fast; and should be 
frequently moved. 

241. Condensing Engines worked on the High-pressure 
Principle. 

In a case of emergency, the mere fact of the condenser 
being useless need not prevent the engines being started. 
The engines can be worked without injection- water, on' 
account of the much greater amount of the steam-pressure 
since the introduction of tubular boilers. In H. M. S. Onyx 
and Yivid, the speed, from being 14 knots, became 9 when 
working in this way. However, since the feed-pumps, as 
at present fitted, only obtain their supply from the hot- 
well, they cannot then be used, and the boiler must be 
supplied by the auxiliary engine or by hand. 

242. Injecting from the Bilge. 

In -case of a ship springing a leak, a vast quantity of 
water may be taken out of the bilge simply by using it for 
injection -water ; and by so doing we are not at all taxing 
the engine, because the engine will require this water to 
perform its work properly. We can form an idea of the 
quantity of water that may be got rid of in this way by 
bearing an mind, that every inch gf water coming away 
from the boiler in the form of steam requires about 80 
cubic inches of water, at the mean temperature, to con- 
dense it. Now the Bee's engine (10-H.P.) demands about 
13,000 gallons, or about 13J tons, per hour for condensa- 
tion ; and we may therefore draw an inference how much 
would be required for larger engines. 

When, however, it is deemed desirable to inject from' 
the bilge, some one should be stationed at the entrance of 
the injection -pipes to keep pieces of chip or oakum from 
getting into them through the roses, or the air will force 
them into the engines, and will eventually stop the engine. 



206 DUTIES TO MACHINERY WHEN UNDER STEAM. 

They will be liable to get into the air-pump, and gag the 
valves, so that the water cannot be pumped out of the 
condenser, and the engine will choke up. This was expe- 
rienced in the* Thunderbolt ; after she was ashore at the 
Cape of Good Hope, a gale of wind came on, and washed 
down the bulkheads, and consequently the oakum with 
which they had been caulked washed into the bilge, and 
made its way into the engine. The Phoenix was found to 
be very leaky lately from a defect in the stuffing-box of 
the screw-shaft ; and in crossing the Bay of Biscay she 
ma*de about a foot more water than the pumps in the ship 
would clear out ; they were obliged, therefore, to inject 
from- the bilge to keep her free: had the injection-pipe 
leading into the bilge become choked up, in all likelihood 
the vessel would have foundered. 

243. On Leaks in the Engine-slides, and their remedy. 
At times it will happen on starting (more especially if 
the engine have been taken to pieces) that the sound of 
air will be heard entering the engine as the vacuum is 
formed. It is sometimes difficult to find out the leak ; but 
it is important that it be discovered, for some tons of coals 
may be saved in a long voyage by having the engine air- 
tight. Many are apt to fancy that a leak admitting air 
into the engine is not so important as one that allows the 
steam to escape. In this, as in. many other instances, we 
are led astray by our senses ; the steam coming into the 
engine-room forces itself on our notice, whereas the air 
can only be discovered by watching for the sound as it 
enters the narrow orifice. One way to discover the leak 
is to light a candle, and pass the flame slowly along the 
joints, when it will be found that, on arriving at the leak, 
the draught of air will force the flame towards the joint, 
whereas at other parts the light will be unmoved. It be- 
comes, therefore, important that the steam should be got 
up twenty minutes or half an hour before the time of start- 
ing, that all these defects may be discovered and remedied. 



LEAKS IN THE SLIDES. 207 

When ready to start, let the engines be blown well 
through, and then let them cool down by the action of the 
external air chilling the condenser. A leak on the steam- 
side becomes visible on admitting steam to the engine, for 
it will make its escape into the engine-room. 

This will also, if the blowing-throngh be continued for a 
long time with the waste-water pipe plugged or stopped up, 
discover a leak on the exhaust side ; but if it fail to do so, 
the candle may be applied aftier the vacuum has been 
formed. If the leak be suspected in a joint where the sur- 
face is horizontal, it will be discoverable by pouring water 
on it ; for it will evidently be at that part where the water 
is forced into the vacuum. 

When the leak has been found, it must be caulked tem- 
porarily with spun-yarn or long hemp soaked in white or 
red lead ; or if the leak do not admit of being stopped by 
caulking, let a piece of soft wood covered with red or white 
lead be driven in. 

In some parts of the engine it will be found difficult to 
make good the defect with red or white lead, from the want, 
of sufficient space in the joint. Suppose, for instance, a 
cylinder-cover be leaky at the joint over the ports, where 
there are no bolts for some considerable space, so that the 
cover springs between the two nearest bolts ; if lead be in- 
terposed, it will be thru'st out by its alternate expansion 
and contraction, and by its want of elasticity will fail to 
stop the leak. The best substance to apply in such cases 
is gasket soaked in red or white lead ; for as the joint opens 
the gasket will spread by its elasticity, and keep the orifice 
closed. If a gasket-joint has been made while the steam 
was down, it should be screwed well up as soon as the en- 
gine is hot, and it will give no trouble afterwards. Gasket- 
joints are very valuable where the surfaces to be brought 
into contact are irregular ; hence they are always used for 
boiler joints, man-hole, and mud-hole doors; but such 
joints as are planed up may be kept air-tight by simply 
14 



208 DUTIES TO MACHINERY WHEN UNDER STEAM. 

interposing linseed-oil or thin white and red lead. Wire- 
gauze is also very serviceable for making joints with. 

244. Method of working the Engines if the Slides are leaky. 
If the slides are leaky, it is advisable to work on the first 
grade of expansion, unless a higher grade be preferred ; 
for with this grade the slide will close the port nearly at 
the same time the expansion-valve closes, after which no 
steam can pass to the condenser, and we consequently save 
the steam that would otherwise pass to the condenser dur- 
ing the interval between the closing of the steam and the 
opening of the expansion valve. 

245. Leaky Condensers or Air-pumps. 
In old engines the bottom of the condenser is apt to give 
out, exposed as it is to galvanic action, from the presence 
of brass in the air-pump and foot-valve, the copper bolts 
in the ship's bottom, etc., the current being excited by the 
moisture in the bilge. Air-pumps become defective in the 
bottom from the same cause. In those engines where the 
air-pump is separate from the condenser, and only con- 
nected with it by means of the foot- valve passage, as in 
Boulton and Watt's old beam-engines, on the bottom of 
such pumps are plates to cover the hole through which 
the boring-bar passed : these plates after a time drop ofij 
the bolts having become eaten away. ITow a defect of this 
kind, whether in the condenser or the air-pump, is very 
difficult to repair while the vessel is at sea, on account of 
the closeness of the part to the bottom of the ship. The 
sleepers would have to be cut away unless it could be re- 
paired from the inside. But the following method will be 
found a good temporary expedient : Let two partitions be 
fitted athwartships between the two sleepers, one before the 
condenser, and the other abaft it ; let also the limber-holes 
be stopped up and be made water-tight, as also the parti- 
tions just mentioned. Again, let a pipe be brought from 
the injection-pipe, or from the water-cock that is fitted to 



LEAKY CONDENSERS, ETC. 209 

qnencli tlie ashes, and, if possible, let this be fitted with a 
stop-cock ; but if that cannot be done, some means must 
be at hand for plugging up the end of this pipe. By means 
of this pipe let us fill the tank we have already made with 
the partitions, and we shall thus effectually cut off the com- 
munication between the condenser and the external atmos- 
phere. If a partial vacuum be created in the condenser, 
the air acting on the surface of the water in our tank will 
force it through the leak into the condenser, and it will act 
the part of a second injection-cock. If the leak be large, 
the injection-cock must be partially closed, as the water is 
getting into the condenser by another channel. It will be 
found in almost all cases that the upper edge of the sleepers 
is above the bottom of the condenser ; so that we should 
have no difficulty in. getting the water to surround the con- 
denser. The tank, or whatever name we please to give it, 
should be kept running over, so as to change the water, 
'and keep the bottom of the condenser cool. There could 
be no objection to having a small quantity of water over- 
flowing into the bilge, for the bilge-pumps would clear it out, 
and it would sweeten the bilge. If the vessel had to run any 
length of time in this way, it would be as well to pitch 
over the bottom of the tank, to cover the heads of the cop- 
per bolts. If a brush cannot be introduced, because of the 
closeness of the condenser to the bottom, it might be melted 
and poured in in sufficient quantities to cover the bottom, 
and cut off the communication with the copper. The water 
should be let out of this tank on arriving in port, or other- 
wise what remains in the tank would become impregnated 
with copper. 

If the condenser be above the sleepers, we must build 
up water-tight bulkheads round the condenser, leaving a 
sufficient space for water all round. We need not remark, 
that we are only by this process approaching to the method 
adopted in land-engines, whose condensers and air-pumps 
are surrounded by cold water. 



210 DUTIES TO MACHINERY WHEN UNDER STEAM. 

246. Feed-pumjos to be hohed to occasionally. 

When -under steam, the feed-pumps should be looked to 
occasionally, to discover whether they are getting out of 
gear ; and in case only one pump is needed to keep up the 
supply of feed-water in the boiler, the means for connect- 
ing the other should be at hand, to provide against the 
danger arising from the water-level being suddenly lowered 
by any accident, such as a shot in action entering the boiler, 
or a leak at other times. , 

The engineer must be strongly impressed with the im- 
portance of keeping the flues or tubes of his boilers covered 
with water while the fires are burning ; for if from any 
cause, whether from blowing-out too freely, feeding too 
scantily, or from the rolling motion of the ship, they become 
bare, not only will they become heated and injured, but 
danger of explosions will arise from the sudden generation 
of steam. To guard against the danger arising from the^ 
rolling motion of the ship, he will find it necessary to keep 
the water-level higher than he would otherwise do. The 
feed-pump should be of sufficient capacity to meet this 
emergency. 

247. Dampers and Ash-pit Doors. 

If a vessel be steaming head to wind and sea, especially 
if it be a paddle- vessel, the number of revolutions will be 
materially diminished ; and therefore, unless the evapora- 
tive power of the boilers be reduced, steam will escape from 
the safety-valve. To prevent an excess in the generation 
of steam, the ash-pit doors and dampers should be partly 
closed; and this is an operation that requires some nice 
management : for if too much closed, the stokers will have 
to rake and knock the fires about, and fuel will thus be 
wasted. If any extra work, therefore, be thrown on the 
Btokers, it is a clear proof the operation has been carried 
to excess. 

248. Meaning of the term ^^ Badc-lashP 
Where parts of the same machine are not rigidly con- 



BEAEINGS OF ENGINES. 211 

nected together^ it will happen that at one time the one 
part will, from its momentum, have a greater velocity than 
the part which ought to remain in contact with it. They 
will therefore separate for an instant. But that portion 
which does not contain within it the moving power must, 
after a time, relax its speed ; and the other part acquiring 
additional velocity, the two will come together again, pro- 
ducing a jar more or less unpleasant and injurious as the 
collision is more or less violent. The series of collisions 
thus produced is called hack-lash. A good illustration of 
this is to be seen in the gearing of screw steamers. So 
long as the driving-wheel endeavors to move faster than 
the pinion will allow it, so long do they remain in contact ; 
but directly the driver relaxes its speed, the pinion sepa- 
rates from it, and the jarring noise is produced when they 
come together again ; for this they must do, since the faster 
wheel is connected with the resistance, and will therefore 
continually go slower, until contact is again made. The 
same thing sometimes happens with the eccentrics of ma- 
rine steam-engines when they are moving slowly. The 
eccentric being loose upon the shaft, and the engine work-, 
ing slowly, it falls away from the stop at one part of the 
revolution ; and, after a short interval of time, the stop 
overtakes it again, and thus a noise caused by their meeting 
is produced. In this case it arises from the eccentric not 
being properly balanced. In some instances, the weight 
balancing the eccentric is too heavy ; in others, too light. 
This may be remedied by tightening the slide-packing, 
or, in some cases, by hanging weights on the eccentric. 

These remarks on the back-lash of the eccentric do not 
apply to the engines for screw-ships which are fitted with 
double eccentrics, for they are keyed on to the shaft, as 
was stated in p. 114, for the head and sternway. 

249. Duties to the Bearings of Engines. 
If bearings are too loose, there will be a disagreeable and 
perhaps dangerous jar; and if too tight, the friction will be 



212 DUTIES TO MACHINEKY WHEN UNDER STEAM. 

too great; they will then get hot, and the attendant evils will 
follow, viz. : the necessity for cold water, frequent stoppages, 
and perhaps a break-down of the engine. It is advisable 
on first starting to have them rather loose, to allow for ex- 
pansion as the different parts get warm. Set-screws are 
fitted to some plomer-block caps to relieve the bearing of 
the weight of the cap, which otherwise acts as a hreah. The 
brasses are also kept off the shaft by screws. Where these 
are not fitted, pieces of hard wood should be interposed 
between the plomer-block and cap, that the wood, and not 
the bearing, may receive the weight of the cap. 

The bearings of some engines require closer attention 
than others : the direct-action class require to be narrowly 
watched. "When the ship is rolling heavily, or pressed with 
sail, the collars of the journals should be well lubricated, 
as well as the journals. Sometimes it is found that oil or 
tallow will not keep the bearings cool ; we must then use 
water ; and this must not be deferred till too late a period ; 
for if we have recourse to water after the engine-bearing 
has become very hot from friction, we may possibly, by 
pouring on cold water, split the plomer-block. The supe- 
riority of water over oil, in many cases, consists in its 
boiling at a lower temperature, and carrying off the heat 
in a latent state, in the form of steam (see p. 33). It does 
not lubricate in the same manner that oil lubricates ; in- 
deed, the friction of the bearings will be greater with water 
than with oil; but by boiling at 212° it keeps down the 
temperature, and thus prevents friction. Both cast iron 
and brass are apt to split from having cold water poured 
on them in considerable quantities when in a very hot 
state. One of the plomer-blocks of a large steamer was 
split in this way. If the bearing be so hot that the appli- 
cation of cold water would be dangerous, let the water be 
applied hot at first, and still the metal will not be raised 
above the boiling-point of water. However, in most cases, 
cold water may be safely applied. Brasses are very apt to 
crack if cold water be suddenly poured on them ; this will 



ON EXPANSIVE WORKING. 213 

be more likely to take place if there be too much zinc in 
the alloy. 

Sulphur, mixed with oil or talloW; will have the effect 
of cooling down a bearing : this seems to be efficacious for 
the same reason that water is so ; sulphur boils at a low 
temperature (226° Fah.), and so the heat is carried off. 

250. "Soft MetaVfor Bearings. 
*'Soft metal" is an alloy consisting of e*qual parts of 
antimony and tin, with a small proportion of copper. The 
proportions are, 19 parts of antimony, 19 parts of tin, and 
9 parts of copper. " Soft metal" does not wear away ; but 
if not confined by edges of brass it will be forced out. It 
is a never-failing remedy for hot bearings ; its effects are 
mechanical, as the bearing alters its shape according to 
the form of the part working in it ; the friction is also con- 
siderably less. The thickness is about a quarter of an 
inch. 

251. On Expansive Working. 

It begins now to be pretty generally understood that 
advantage is gained by working steam expansively. The 
advantage over that obtained by throttling arises from the 
circumstance, that though the steam has but a small pres- 
sure at the end of its stroke, and therefore a cylinder full 
of very weak steam is used, yet during a portion of the 
stroke, that is, during the portion the piston traverses be- 
fore the steam is cut off, it has a considerable degree of 
elastic pressure, much greater than it would have if the 
steam were throttled. Again, we know that even if the 
steam be partially throttled, we shall be able to work more 
economically than if we used the full power of the engine ; 
for, although the vessel would not go so fast, the same 
qiiantity of coal would, unless during boisterous weather, 
with opposing winds, make her traverse a greater space. 

But when steamers are working expansively, and they 
have to stop from any cause, more particularly in cases of 



214 DUTIES TO MACHINERY WHE^T UNDER STEAM. 

collision, tlie expansive gear should be thrown o& before 
attempting to start again ; for, supposing the engine to be 
working with a high grade of expansion, and the order is 
given to stop, and then to start again, the cranks of both 
engines may be in such a position that no steam will enter 
so long as the expansive gear is in connection with the 
engine, for both expansion- valves may be closed at once. 
Let us suppose, for instance, that the steam is cut off 
when one quarter of the stroke has been accomplished, 
and that the engine is stopped with one of the pistons 
near the half-stroke, and descending; the other crank 
will be approaching its lower centre, neither of the ex- 
pansion-valves will be open, and therefore, though the 
slide be moved by hand to admit the steam, no motion 
will ensue. 

Again, if the order be given to go astern, the expansive 
gear must be disengaged before executing the order, be- 
cause the expansion-cams are not constructed so as to 
admit steam for the back motion. 

252. Steam Circle. 
When it is intended that a steamer should make use 
of the combined advantages of steam and sail, the follow- 
ing rule, suggested by Captain Eyder, E.N., may be found 
of some practical utility. On steaming directly towards a 
port with a foul wind and sea, should it become apparent 
that the quantity of coal remaining on board is not sufli- 
cient to enable the ship to reach the harbor, and it 
therefore becomes necessary to keep her off under sail, 
putting out the fires or banking up, as may be deemed 
expedient, it may become useful to estimate the quantity 
of coal remaining on board in miles of distance from the 
port ; then opening the compasses to that distance, accord- 
ing to the scale of the chart, place one leg on the port to 
be reached, and describe a circle round it, which call the 
" steam circle." It will then be evident how long the ship 
must be kept under sail before the distance can be reached 



MANAGEMENT OF FUEL. 215 

at wnich she could arrive at the port under steam alone ; 
and if from the place of the ship two tangents be drawn 
to the circle on opposite sides of it, we shall be able to see 
how many points the ship may be kept away so as to get 
with certainty within the steaming distance by the assist- 
ance of sail only. 

253. On the Mariagement of the Fuel while under Steam. 

The coal-boxes require to be looked to occasionally, to 
see if there are any symptoms of spontaneous combustion. 
If there be, no time should be lost in well deluging the 
coal-box with water; and the precaution of not taking off 
the scuttles should be carefully observed, so as not to 
allow a free supply of air, except in that one through 
which the water is to be poured. Some steamers are 
•fitted with pipes leading down the coal-boxes, and filled 
with water. These pipes serve to indicate the temper- 
ature of the coal-boxes at intervals ; for if the coals be- 
come hot, the heat will be conveyed by the water up the 
tube to the surface, and by ascertaining the temperature 
of the water we can readily tell whether all is safe in the 
^ interior of the mass. 

If the steaming qualities of the boiler are sufSciently 
good, the coal should be wetted, if small, before being put 
on the fire. With Welsh coal, and particularly if the coal 
be small, it will be found to be a source of great economy 
to wet it ; for if the coals be thrown on small, a great por- 
tion is carried onwards to the tubes, flues, etc., stopping 
them up with soot (a non-conductor). Again, small coal 
will lie on the top of the fire like so much sand, and the 
air cannot get at it to produce a speedy combustion. And 
if the fire be disturbed, or raked about, to make it burn 
better, the small coal passes down between the fire-bars, 
and, in all probability, is cleared out of the ash-pits with 
the ashes, and eventually thrown overboard. Hence it 
will be found that by wetting the coal steam will bo kept 
better, and with the consumption of considerably less fuel. 



216 DUTIES TO MACHINERY WHEN UNDER STEAM. 

In Wales it is a common practice to mix up small coal 
with water, or even with mud, so as to enable them to be 
formed into balls, and they thus make exceedingly good 
fires. 

254. Preparatory Orders hefore Stopping the Engines. 

Fuel may be saved if the engineer be made 'acquainted 
beforehand with any stoppages likely to take place ; as, 
for instance, for getting soundings, coming to an anchor, 
or taking a ship in tow, or whenever the speed of the 
vessel is about to be reduced. As an extreme case, let us 
consider a vessel of the size of the Terrible, when working 
all her boilers, with twenty-four fires ; suppose an order 
to be given to stop the ship immediately after the fires 
have been fresh charged with coal. N'ow each fire re- 
quires about three or four shovelfuls of coal, or about 
20 lbs. Therefore all the fires will have required 20x 24 
= 480 lbs., nearly a quarter of a ton. If immediately 
after "firing the ship be stopped for some time, this fuel 
will evaporate water from the boilers, and the steam 
generated will escape by the waste-steam funnel, whereby 
so much coal will be wasted, at the same time causing a 
great noise on deck from the rush of steam, and prevent- 
ing orders from being distinctly heard, all which might 
have been avoided if those in charge of the engine-room 
had been made acquainted with the stoppages likely to 
take place. In giving the orders, however, it would be well 
that they were given in such a way as to leave the man- 
agement and responsibility of the fires in the hands of 
the chief engineer: it might be productive of bad con- 
sequences to order the engineer not to put on any more 
fuel for a certain time, because those on deck cannot be 
aware of the state of the fires at the time they give such 
order. The engineer not being allowed, after such an 
order has been given, to exercise his discretion, complies 
with it literally ; and if the vessel is going at her full 
speed, the steam-pressure falls, because the demand is 



PEEPAEATORY OEDERS BEFORE STOPPING. 217 

greater than tlie supply ; and should she stop, and it be 
found necessary to give a back-turn, it might be impossi- 
ble to do so. This is to be particularly guarded against 
in crowded harbors. 

When about to stop a steamer, for any reason what- 
ever, it is a useful rule to give the previous order to the 
engineer, "Stand by below;" for in large steam-ships it 
requires nearly all the engineers, and in some ships quite 
all, to work the engines by hand. This order will there- 
fore enable the chief engineer to place his men at their 
stations, and so prevent confusion and loss of time. In 
some steamers, fitted with single eccentrics, when under 
way, the gear for working the slides is detached ; and 
the order, "Stand by," gives time for the engineer to 
make his arrangements, and carry out the coming order 
quickly. Again, if the order, " Down with the engines," 
be given after the vessel is fast, it is conducive to the sav- 
ing of fuel : for otherwise the engineer, not knowing what 
is likely to occur, keeps the fires forward, and perhaps the 
dampers open ; or, in other words, keeps the fires in such 
a state that the engines can be instantly moved if wanted ; 
whereas if he had been aware the vessel would not have 
to start again for some time, and that he should have 
timely notice previously, he would have put the fires back 
and closed the dampers, and then a certain amount of fuel 
would have been saved ; or if the stoppage were for any 
length of time short of two hours, he would have " banked 
up." (Seep. 178.) 

This last evil would be greater in tubular boilers, in 
consequence of the water being so soon evaporated, and 
from the incessant working of the auxiliary engine when 
the vessel is stationary, to say nothing of the unpleasant 
noise arising from the steam blowing off. 



CHAPTER YII. 

DUTIES TO MACHINERY DURING AN ACTION OR AFTER AN 
ACCIDENT. 

255. The Gear for repairing Damages during an Action. 

■ All tools that are likely to be wanted should be arranged 
in order in the engine-room, according to the discretion of 
the chief engineer, in some place where they will not be 
liable to be struck with shot. Inside the combings 'of the 
hatchways would evidently first suggest itself as the most 
suitable place for such gear as might be wanted on deck ; 
but such places are too liable to accident, and therefore- 
the engineer must be content to put up with the delay occa- 
sioned by sending below for whatever articles he may want. 
The following gear should be ready and arranged : 
Spanners suited to the paddle-wheels, as many as the 
ship is supplied with ; hand, sledge, and flogging ham- 
mers ; punches, flogging, cross-cut, and hand-chisels ; three 
or four hack-saws ; some fearnaught, canvas, thin sheet- 
iron and copper plates, swabs, spun-yarn, and shores of 
convenient length ; also plugs for the tubes of the tubular 
boilers ; spare sails, hammocks, etc. ; and bags of coal, if 
time will allow, should be placed round and on the steam- 
chest, especially if the vessel be likely to be fired on from 
a height. 

256. Machinery requiring examination hefore the Action. 
The disconnecting gear should be in such good work 

ing order as to leave no doubt as to its efficiency ; but if, 
from any cause, we are not quite certain of it, this should 
be examined, if time permit, because it may happen that 
a shot or shell will so distort one of the wheels that the 
vessel will be useless until it be disconnected. 
218 



PRECAUTIOJ^'S AGAINST FIRE. 219 

Also the bilge-pumps should be connected; and the 
apparatus for the process of injecting from the bilge care- 
fully examined. 

Kote. — Care should always be taken to replace all the 
tools after each part of the machinery has been examined, 
to be in readiness when actually wanted. 

257. Preparations to he made in the Engine-room against 

Fire. 

The boiler hand-pump should be in readiness to supply 
water in case of fire, and the hose should be screwed on 
previously. In some steamers, a pipe from the feed-pump 
is brought on deck to supply water ; this also is an advan- 
tageous plan, especially if the ship were attacked by pirates, 
where the laws that usually regulate modern warfare are 
neglected; for if the engine be worked hot, hot water 
would be ejected from the pipe. 

258. Regulation of the Fires during Action. 
This must depend entirely on the nature of the service. 
If the steamer be chasing an enemy^s ship, or, on the 
contrary, be trying to avoid the fire of a superior force, 
or if the vessel be liable to be sent off with all speed to 
take up some other position, or to carry reinfrrcements ; 
or in towing ; or, in short, in any important duty where 
all the power she can command will be required to be 
brought into play — it is plain that in any such case the 
steam must be kept up at its full intensity, or nearly so, 
at whatever hazard. But, on the other hand, if the 
s,teamer be employed in bombarding, as was lately the 
case at Odessa, where speed was no great object, and the 
ships were merely kept moving to divert the attention of 
the enemy ; or, again, in a general action with other ves- 
sels, when there is no probability of her being required to 
ahange her position without some minutes previous notice 
— then in all such cases it becomes important to allow the 
steam-pressure to decrease till it is but little above the 



220 DUTIES TO MACHINEKY DURIXG AN ACTION. 

atmosplieric pressure : and tlie reason is obvious, for we 
know that if a shot enter a boiler filled with very strong 
steam, steam or water, or both, will rush out with disas- 
trous effect into the engine-room, creating great mischief 
and confusion ; whereas, on the contrary, if the steam 
have not a pressure much exceeding that of the atmos- 
phere, the damaged part becomes much more manageable. 
It must be remembered that should the steam be lowered 
to the atmospheric pressure, the gauge-cocks will not act ; 
and it will be impossible to change the water in the boiler, 
if the water-level be lower than that outside the vessel. 
Hence, whenever the authority of the commanding- of&cer 
sanctions such a step, let the steam be lowered till near 
the atmospheric pressure ; and as this requires some little 
management, we will go somewhat into detail. Let the 
fires be banked up so as not to burn too briskly, and yet 
be in such a state that, by raking the coals about, a good 
fire may instantly be excited ; this will enable the vessel 
to start off shortly after the order to do so is given. The 
next important thing to attend to is the reverse- valve ; 
for we have already seen that when the pressure in the 
boiler becomes much less than that of the atmosphere, 
this valve opens, and allows air to enter. ISTow if the en- 
gine have to work at this low pressure — as, for instance, 
to enable the ship to shift her birth, etc. — the efficiency 
will depend more on the state of the vacuum than that of 
the steam ; and the vacuum will evidently be much in- 
jured by the introduction of air into the boiler, so as to 

.become mechanically mixed with the steam. This is of 
more importance in unbalanced than in balanced enginesj^ 
for atmospheric steam entering below the piston will at 
best have as much as it can struggle with in raising the 

3 piston, more particularly if there be a head wind and sea. 

^Let, therefore, the reverse-valve be temporarily loaded, 
and fit a longer steam-gauge float than that ordinarily- 
used, to enable the engineer to discover the state of the 



PADDLE-WHEELS LIABLE TO BE STRUCK. 221 

steam,* and so to manage the fires as to prevent a vacuum 
from being created within the boiler. The reverse-valve 
should be loaded so as to open when the external pressure 
exceeds the internal by about 5 lbs. 

Another plan may also be tried, which perhaps would 
be more advantageous than the preceding. Keep the fires 
forward, and in an active state of combustion, and open 
the safety-valve to allow the steam to blow off to atmos- 
pheric pressure. But if the steam-chest be small, it will 
perhaps be found that air will enter the boiler by the 
safety-valve whenever the engines are worked according 
to this plan, particularly if the orifice of the internal 
steam-pipe is near the safety-valves ; for the rush of steam 
to fill the cylinders is so great that a partial void is ere 
ated, and the air rushes through to supply the place. 
Should this be found to take place after the steam 'is 
blown off, the safety-valve may be partially closed to pre- 
vent air from entering the boiler. 

259. Casualties to which Paddle-wheels are liable during 
Action. 

They are necessarily liable to be struck by shot, and 
disabled ; but the chance of their being disabled seems to 
have been much magnified by alarmists. Indeed, previ- 
ous experience does not allow us to bring forward any in- 
stance of a steamer's wheel having been disabled in action, 
although the ship has been struck in the hull in a great 
number of places.f If, however, the wheel happen to be 
struck, and it be found to revolve afterwards with the 
engine, let it continue to work ; for the steaming qualities 
of the ship will be but little affected, although two or 
three paddle-boards and arms are knocked away. A 

* There is now no chance of the mercury being forced into the 
boiler from the pressure of the air, because in the present day an in 
ternal pipe is carried up from the steam-gauge to the upper part 
of the steam-chest. 

t Mackinnon's Steam Warfare in the Parana, vol. i. p. 220. 



222 DUTIES TO MACHIIs-ERY DURING AN ACTION. 

steam-sMp when on tlie coast of Africa worked tlie en- 
gines with one-third of the paddles off eaj^h wheel. She 
had been sailing, and, wanting to go in chase, did not 
wait to ship the floats. But if it have become so jammed 
as to prevent the working of the engine, it must be dis- 
connected immediately from the engine, and the ship be 
steamed with the one wheel; this will give her about 
two-thirds her full speed. One engineer at least must be 
present at the work of removing the damaged parts of the 
wheel, with handy workmen who have been used to ham- 
mers, etc. The tools required will be principally flogging 
chisels and hammers.* 

260. General effect of Shot upon Funnels. 
The danger from shot is not much to be apprehended, 
unless its velocity has been partially destroyed before 
striking the funnel. It was formerly supposed that flame 
would escape from a shot-hole, and be productive of dan- 
ger to the ship ; but serious reflection will convince any 
person that, on the contrary, the cold air will rush into 
the funnel, where the gases are much rarefied by heat. 
This was fully tested on board H.M.S. Echo. The draught 
will be slightly checked by the cold air rushing into the 
orifice, but not suflS.ciently so to produce any appreciable 
difference in the speed of the ship, or in the revolutions of 
the engine. And even if a spent shot or a falling spar 
strike the fannel, and carry it away, the chief mischief 
that will accrue will be, that the draught will be lessened, 
and the men on deck will be annoyed with the smoke ; 
but the evil is not so great as might be supposed.f What 

* It may not be out of place here to remark, that during a war, an 
engine-smith and a boiler-maker should be attached to the engine- 
room. Our West-Indian mail-packets are manned in this way. 

t This has been sufficiently tried on board her Majesty's ships 
Blenheim, Echo, and Bee, by direction of Captain (now Eear- 
Admiral) Chads, E.N. In the Bee, the effect on the speed from 
entirely removing the funnel was a loss of about one-fifth. 



EFFECT OF SHOT UPON FUNNELS. 223 

we have to dread most is, that from some misclaance-^ 
perhaps from t^e effects of a falling spar — the funnel will 
be bent down, because it will in its fall carry over with 
it the pipe by which the st^am makes its escape ; for if 
this pipe be merely bent over, and not carried away en- 
tirely, the steam will be stopped, from its not being able 
to pass the bend. 'Now let us bear in mind, that the fun- 
nel being bent over prevents the production of steam by 
checking the draught; and that the same accident hap- 
pening to the waste-steam funnel prevents the overplus 
steam from getting away from the boiler. It becomes, 
therefore, a duty, before cutting away the funnel and 
liberating the smoke, that the waste-steam funnel should 
be cleared away to enable the safety-valve to act freely : 
if the vessel be in motion, so much the better, because 
the engines will then consume the steam as fast as it is 
generated, and prevent accumulation in the boiler. But 
the evil may be yet more serious ; for it may happen that 
the engine is stationary at the same time the steam-fun- 
nel is bent down, in which case there will be no vent for 
the surplus steam till the orifice be opened ; and unless 
this be done expeditiously, the steam will accumulate 
in the boiler, causing an explosion. In addition, there- 
fore, to the obvious method of cutting off the injured 
pipe, some prompt measure should be adopted to prevent 
a great accumulation within the boiler. To haul out the 
fires would but increase the danger; for the very aci 
would put the fires in such a rapid state of combustion, 
that an additional quantity of steam will be rapidly gen- 
erated. Again, the future production of steam will be 
checked by this process ; and it would be very imprudent 
at such a time to put a stop to the further service of the 
engines. Let, therefore, instead of this, the blow-valve be 
opened; and that the steam may not inconvenience the 
engine-room, if the vessel have light draught of water, let 
the snifting-valve be weighted, or even shored down for 
the time that the steam may be driven up through the 
15 



224 DUTIES TO MACHINERY DURING AN ACTION. 

ak-pump, hot- well, and lastly througli the waste-water 
pipe into the atmosphere. Should the "poller be over- 
taxed by this, as can easily be ascertained by the steam- 
gauge, let the grease-cocks on the cylinder-cover be opened, 
or the upper escape-valve, and let the slide be placed in 
such a position as to allow the steam to enter the cylinder 
above the piston. A weight may also be put on the re- 
verse-valve ; or if an inverted one, it may be shored up. 
The boiler would by these means be relieved ; and on the 
order being given to go on, the engine could in an instant 
be brought into its normal state, and the working of the 
engine would carry off the steam. In doing all this, it 
may happen that the condenser will have been made so 
hot by the bio wing- through that the injection- water will 
not come into the condenser. If so, let a few buckets of 
eold water be thrown over the outside of the condenser, 
if possible, and work the engine as slow as circumstances 
will admit, keeping the injection-cock open. Even at the 
worst the engine can be worked for some time at high 
pressure, if the boiler is loaded to 8 or 10 lbs. This will 
work off the steam, and save the boiler. 

It may be possible to work the engines for a short time 
by going alternately ahead and astern, even though tho 
vessel be not permitted to shift her berth to any great dis- 
tance ; and in such case this might be done. 

261. Remedies to he ado'pted in case a Shot enters the Boilers. 
If the shot make an orifice in the water-space of the 
boiler, hot water will immediately rush out. Let all the 
scuttles in the stoke-holes be open, that the water may 
find its way into the bilge ; and let the spare gratings be 
handed down from the decks as quickly as possible into 
the stoke-hole for the stokers to stand on while firing, 
especially if one boiler only is struck. If the steam be 
above the atmospheric pressure, let it be allowed to escape 
by the safety-valve, open the blow-out cocks of this boiler, 
put the fires back if they can be got at, close the dampers 



EEPAIES TO BOILEE. 225 

and ash-pit doors, use the steam from the boiler alone ; 
then the water Vill not be forced out of the boiler, but only 
run out as it would from any other vessel, the force de- 
pending on the height of the surface of the water above 
the orifice. If the shot, however, enter the steam part of 
the boiler only, and the steam be only at atmospheric 
pressure, it will be of no consequence so far as the effect 
in the engine-room; but if it be at a pressure much above 
that of the atmosphere, it will scald all those who- come in 
the direction in which it is issuing. The hole through the 
boiler may be stopped by placing a piece of wood against 
it, which may be kept in its place by a shore from the 
ship's side, etc. A piece of feafn aught, covered with red 
and white lead, should be placed between the wood and 
the boiler to render it water-tight. 

262. Whether the Steam should he got up in all the Boilers on 
going into Action. 
It would be advisable to get up the steam in all the 
boilers, even though all be not wanted, and the fires should 
be banked up in those that are not used ; for, first, no one 
can tell from one minute to another what need the vessel 
may have of all her power ; and secondly, the chances are 
much against all the boilers being struck with shot. The 
steam might be kept very low in those boilers not imme- 
diately wanted, but yet in such a state as to be readily ser- 
viceable if required. 

263. Temporary Repair to the Shell of a damaged Boiler. 
It has been previously stated, that iron plates should be 
prepared, of different sizes, to suit any case that may 
occur. Let these have one or two holes in the centre, with 
cross-bars and bolts, together with nuts to screw up the 
plates, somewhat similar to the man-hole . and mud-hole 
doors. A portion of these patches (half, for instance) 
should be concave ; so that, when having to patch a boiler 
on the side opposite to that by which the shot entered, the 



226 DUTIES TO MACHmERY AFTER AN ACCIDENT. 

convexity will allow the edge of tlie patcli to come close 
home. With, every patch provided, there should be two 
or three layers of fearnaught, that the joint may be made 
tight. If repairing on the side by which the shot entered, 
no great difficulty probably will present itself beyond that 
of getting the bar in the hole ; but on the other side many 
of the ragged pieces of the edge will have to be first 
broken off, the fearnaught must be interposed between the 
plate and the boiler, and the plate must be screwed home 
towards the bars, interposing washers between the plate 
and the nut, to save time. The side of the boiler by which 
the shot makes its egress will present by far the most for- 
midable difficulties ; for, in addition to the jagged appear- 
ance of the shot-hole with the pieces projecting outwards, 
the fragments splintered off the other side will probably 
make a vast number of ragged holes of various sizes. 

264. Steam-pipe or Feed-pipe struck with Shot. 

K the steam-pipe be struck, the stop or communication 
valves riiust be immediately closed, and a handy piece of 
sheet iron or copper must be curved to suit the form of 
the pipe. A layer of fearnaught should be interposed be- 
tween the sheet and the pipe ; and the whole may be 
secured by spun-yarn wound round it. 

If the feed-pipe be struck, and the small engine for 
feeding the boiler be efficient, that must, of course, be set 
to work, and the feed- apparatus be detached ; but if that 
have been already disabled, it may be that the boilers are 
fitted with circulating-pipes ; then feed into one boiler by 
that feed-pipe which is still in working condition, and open 
the communication between the two boilers ; or the blow- 
out cocks may be opened if they happen to lead into one 
of Kingston's valves. If no such pipes are fitted, we must 
resort to the following plan : Go on for some time without 
feeding, that is to say, as long as is consistent with safety, 
and then blow the steam off from the boiler requiring to 
be fed ; and if the boiler's water-level be below the water- 



WOEKING WITH ONE ENGINE. 227 

line outside; all we have to do is to open the blow-off 
cocks, and the water will rise in the boiler to the level of 
the water outside the vessel : this process may be repeated 
from time to time, until the feed-pipe has been temporarily- 
repaired, which can be done after the same manner as the 
steam-pipe, that is, with a piece of sheet-copper, canvas, 
white-lead, and spun-yarn. 

If the waste- water pipe be broken from any cause, the 
engine must be worked without condensation, to lessen 
the quantity of water that would have to pass through the 
pipe. If the injury can be got at, a strong cleat may be 
nailed to the ship's side, and pieces of wood secured to 
this and round the pipe ; the whole being wrapped round 
with canvas, white-lead and spun-yarn, forming a sort of 
faucet or expansion-joint. 

In the case of sea-cock pipes breaking at the vessel's 
bottom, as has sometimes happened, a similar plan should 
be adopted. 

265. To work with one Engine only if the other he disabled. 

If one of the engines be disabled by any accident, and 
the other be required to work the ship, there may be some 
difficulty in making it pass the centres, especially if it be 
a paddle-steamer worked by a direct- action engine. 

If the nature of the service allows, no time should be 
lost in taking off some of the paddle-boards at that part 
of the wheel where the weight of the piston is felt. If, 
for instance, the wheel be fitted with double boards (the 
cycloidal wheel), let one of the boards be detached from 
each of the arms of both wheels that happen to be in the 
water when the engine is in that position in which it is 
brought to a stand-still. If the wheels be fitted with single 
boards,* let all the paddle-boards be reefed, and thus lessen 

* The divided boards are to be preferred for several reasons, .par- 
ticularly because they are not so liable to split, and are more easily 
removed in parts when fitted as a common board, that is, placed on 
the same side of the paddle-arm. 



228 DUTIES TO MACHINERY AFTER AN ACCIDENT. 

the work of the engine : this, indeed, seems the best way 
even with the cycloidal plan, for it will let the single en- 
gine come up to its work, and use its steam ; but those 
paddles which would be in the water when the steam has 
to contend with the disadvantages of the engine, should 
be brought nearer to the centre than the others, so as to 
give an oval form to the curve made by the outer edge of 
the paddles. If, owing to stress of weather, being chased, 
or from any other cause, it is found impossible to re-ar- 
range the floats, so as to enable the single engine to turn 
its centres with facility, it may be found necessary, on first 
starting after the accident, to put the ship before the wind, 
that the way of the ship may assist the cranks over the 
dead centres till the engine have acquired sufficient mo- 
mentum ; after which, on hauling to the wind again, the 
engine will probably continue to work. As the top centre 
in direct-action engines offers the greatest difficulty, the 
lead may with advantage be dispensed with by lowering the 
slide a small space. With all kinds of marine engines, in 
whatever duties employed, whether in towing, running 
with mails, or for war-purposes, the engines should be so 
managed as to move with the normal velocity of the piston 
at least, or rather above it ; and this more particularly if 
the engine be leaky on the exhaust-side so that the quick 
working of the air-pump will keep the exhaustion, much 
in the same way as a man does who works the handle of a 
common hand-pump quickly when the bucket is leaky. 

266. Remarks on the Screw- Propeller. 
One great object aimed at by the constructors of engines 
to work the screw-propeller has been, to keep every part 
below the water-line of the ship, thereby protecting them 
in great measure from the effects of shot ; and therefore 
the precautions and rules laid down in the former pages do 
not apply with so much force to them; although, if any 
accident were to happen, the same system must be pur- 
sued. The screw, however, is liable to be struck if the 



NECESSARY PRECAUTIONS. 229 

vessel be pitxiliing at all heavily, and doubtless the mis- 
chief would be greater in such case than if a paddle-wheel 
were struck. If a part be hrohen away by any accident, 
and the screw be found to revolve, let it go on ; remem- 
bering that, since the surface of the blade is diminished, 
the engines will go too fast, and exhaust the boiler ; to 
prevent which, the engines must have their power reduced 
by working expansively, or throttling the steam. If the 
screw be injured by becoming twisted, without being 
knocked clean away, so as to be jammed in the space cut 
out for it to work in, no general remedy can be stated ; 
but it must be left to circumstances, depending entirely on 
the nature of the injury,- and the time, opportunity, and 
means th6 engineer can command. 

267. A Steam-Ship leaky, when the Steam is not required. 

, We could evidently disconnect the paddle-wheels or 
screw from the engine, and work without them, employing 
the steam-power solely in pumping out the vessel. To do 
this, we must connect the bilge-pumps, and inject from the 
bilge. A considerable quantity of water may be allowed 
to enter to the condenser ; because the engine working so 
freely, the air-pump will carry it off, and therefore we can 
let in much more water than is sufficient to condense the 
steam. If the engine be unbalanced, and any difficulty 
occur from its want of power to turn the centres after 
having lost its paddles, which serve as the fly-wheel, the 
slide-rod should be lengthened a little, which can be readily 
done in most engines ; consequently the cushioning on the 
down-stroke will take place sooner, and the steam will 
come in earlier ; this will prevent too great a downward 
momentum ; and, on the other hand, the steam will be ad- 
mitted for a longer portion of the up-stroke.* 

268. Necessary precautions if the Vessel be so disabled that 

she must go ashore. 
The first object should be to increase speedily the ves- 

* See Indicator and Dynamometer, 2d edition, p. 25. 



230 DUTIES TO MACHINERY AFTER AX ACCIDENT. 

sel's draught of water, that she may take the ground as 
early as possible ;* so that when all is ready to get her 
off again, she may be lightened. The boilers should, 
therefore, be filled up by the pumps to their crowns, and 
water should also be allowed to enter the bilge. A good 
way to effect this latter object is to let the injection-cock 
be opened, and allow the water to find its way through 
the snifting-valve. 

269. Temporary Re;pair of Tuhes when damaged hy Shot or 
any other cause. 

The remedy in this case is obvious : all that can be done 
temporarily is to prevent the water from entering the 
smoke-box ; this can be done by driving plugs into them. 
In some cases, both ends of the tubes must be plugged up ; 
but frequently it will suffice to drive a plug into the tube 
so as to cover the hole. The plugs should be made of a 
good length, so as to cover more than one hole. 

If several tubes are destroyed at once, so as to render 
all attempts at repair abortive, the fires should be drawn 
from that boiler, which must be considered hors de combat. 

270. Steamers in Chase. 
When two steamers are keeping the same course, and 
one of them has some slight advantage over the other in 
speed — say a mile an hour — then if the slow vessel can by 
any means get so close on the quarter of the other as to 
be powerfully influenced by the following current of the 
faster vessel, it will be found that the latter will not be 
able to escape from her ; and the other, although slower, 
will be enabled to hang upon her quarter as long as she 
pleases, unless by skilfully altering the course the faster 
vessel make her escape in another direction. It is a com- 
mon thing to see one steamer huggingf another in this 



* See the Recover^/ of H.M.S. Gorgon, p. 6, by Captain A. C. 
Key, RN. 

t This is the term used on the Thames. 



REPAIRING SHOT-HOLES. 231 

way. The only way to avoid it in the faster vessel is by 
suddenly and unexpectedly altering the course, so as to 
change the direction of the current before the chasing ship 
can be aware of what is done. 

271. Repairing Shot-holes in the Funnel after an Action. 

These may easily be repaired by having some patches 
of thin sheet-iron got ready, with a sort of double spring 
attached, one inside and the other outside ; the hole may 
be covered over by one of these patches, since we need 
not be very careful about its fitting over-tightly. To do 
away with the fear that exists in many minds lest the fire 
should come out of these holes, we would instance the 
doors in front of the smoke-boxes of tubular boilers that 
are made to ship and unship, and no risk of burning the 
vessel by the issuing flame is ever entertained. 

The observations we have already made respecting the 
mode of repairing, in a temporary way, the damages of 
boilers during an action, will apply to them after the ac- 
tion is over ; only greater care and more precautions can 
be adopted than would otherwise be used. If the hole be 
in such a part that a shore may be interposed between the 
orifice and the ship's side or the beams overhead, we may, 
in addition to the plans proposed, press home the plate 
against the fractured part by these means. In many in- 
stances, however, it would be better to empty the boiler, 
and allow the patch to be introduced from the inside, that 
the pressure of the steam may make it fit more tightly, 
instead of tending to force it away. To get an idea of this 
method, we would refer our readers to the mud-hole doors, 
the plan proposed being similar in principle. 

272. Necessary precautions when straightening a Piston-rod, 
or other part of the Machinery. 
To effect a repair of this nature, the part must be put 
in the fire and softened. Now in doing this, if it be ex- 
posed to the open air when hot, it will oxidate, and por- 



232 DUTIES TO MACHINERY AFTER AN ACCIDENT. 

tions will scale off; to prevent whicli, the fire that is used 
must be chiefly of wood, for coal brings off scales from 
iron when heated to redness. The same reasoning applies 
to some other parts of the engine ; for instance, if a crank- 
pin or crank-shaft were to scale, the pin would be too 
small for the eye of the crank. Charcoal should be used 
if it can be had. 

273. Method of working the Engines without Cylinder-covers. 
It can be effected in this way : Let the broken cover be 
removed, and the upper steam-port blocked up with a 
piece of wood so shaped as to prevent its being forced in- 
wards towards the slide by the pressure of the atmosphere : 
the orifice is made steam-tight by interposing fearnaught 
between the wood and the edges of the port. The wood 
must be kept in its place by two shores, one on each side 
of the piston-rod, pressing with one end against the wood, 
and with the other against the opposite side of the cyl- 
inder. The steam will be admitted, therefore, to the under 
surface of the piston, but not to the upper surface : the 
upper surface will be acted on by the atmosphere alone.* 
Now, since the pressure to which the steam is raised is 
considerably above that of the atmosphere, the piston will 
be forced up against the resistance the air exerts ; and on 
creating a vacuum underneath the piston, it will be forced 
down by the atmosphere. To prevent irregularity, we 
should not create too good a vacuum ; thus, if the steam 
have a pressure of 10 lbs. above that of the atmosphere, 
we have an effective upward pressure of 10 lbs., and con- 
sequently the downward pressure should be about 10 lbs. 
But the pressure of the atmosphere is 15 lbs. ; hence we 
should have a pressure underneath of 5 lbs., arising from 

* "We have throughout this work used freely the words upper and 
under : when speaking of the sides of the piston, these expressions 
apply strictly to upright cylinders only ; but it will be understood 
that when speaking of horizontal cyUnders, the opposite slides are 
meant. 



WORKING ENGINES WITHOUT CYLINDER-COVERS. 233 

the uncondensed steani; or a deficiency from a vacuum 
amounting to 10 inches of mercury ; and since a perfect 
vacuum amounts to 80 inches, the height of the barome- 
ter-gauge should be about 20 inches. Subsequent ex- 
periments have, however, shown that this precaution is 
usually unnecessary, and need only be adopted when un- 
pleasant jerks are experienced as the wheels rotate. The 
vessel's rate was found to be about two-thirds her ordinary 
speed. If the engines be fitted with Seaward' s slides, we 
need only detach the upper slides on the steam and vacuum 
sides ; the springs at the back will be sufficient to press 
them against the part and keep them closed. This was 
successfully carried out in the Reynard. 



CHAPTER YIII. 

DUTIES TO ENGINE, ETC., ON AREIVING IN HARBOR. 

274. Blowing-out on arriving in Port. 
It was formerly the universal practice, and is continued 
now in many instances, to empty the boilers by " blowing 
out ;" but the introduction of tubes, in many cases made of 
thin brass, has rendered this practice objectionable. For 
it has been found, from the contraction of the tubes on 
cooling, leaks have been caused in the tube-plates. And 
consequently the boilers are now allowed to cool gradually 
with the water in them ; and if it be thought right to have 
the boilers empty, the water is pumped out afterwards. 
The chief thing for consideration is, that hot water will 
hold many salts in solution that will be precipitated when 
cold, and therefore previous care should have been taken 
to have the water well changed. The general practice at 
present is to " blow out" until the water is as low as is con- 
sistent with the safety of the tubes, and then pump the 
boilers ap again by the donkey-engine before hauling out 
the fires. The safety-valve should be allowed to remain 
closed, to prevent the water from becoming more saturated 
with salts. 

275. Blowing through and hauling out Fires, 
The engines should be blown through with steam the 
last thing, to dtive all the water out. The cock at the 
bottom of the condenser is also useful for this purpose. By 
taking due precaution, much of the injury to engines from 
the oxidation of the metal will be prevented : another 
source of risk will also be avoided ; for, as was observed 
234 



ON ARRIVING IN PORT. 235 

in Art. 201, in frosty weather there is danger of solid ice 
being formed in the engines, as, for instance, above the air- 
pump bucket. On one occasion a steamer was detained 
for hours while attempts were made to melt it ; and when 
the engines began to move, fears were entertained that the 
air-pump covers would give way. 

When the fires have been hauled out after anchoring, it 
becomes necessary to deluge the burning fuel with water. 
A ship from neglecting this had to be scuttled : the stoke- 
hole plates became red-hot and set fire to the platform 
underneath, and this again to the coal-boxes. 

276. Duties to the Engines on first arriving in Port. 
The engines should first of all be carefully wiped down, 
after the boilers have been blown out ; for while hot the 
grease is more easily removed, and it can be done with 
less waste. When this has been done, if the vessel is to 
be laid up for any considerable time, the packing should 
be taken out of the slides, glands, etc., for if not, a galvanic 
action is set up, and the rods, etc., will oxidate rapidly ; 
but otherwise some melted tallow should be poured into 
the grease-cups round the piston-rods : the object of this 
is to prevent the entrance of dirt between the bush and 
the rod. This tallow must be allowed to remain there all 
the time the vessel is in harbor, to catch the dirt that 
would otherwise fall into the gland, or get down between 
the piston-rod and the bush, and having once found its 
way there, would cut the rod and wear away the packing. 
A similar plan should be adopted with all the other glands. 
When the steam is getting up, we are not to allow this 
tallow to remain there and melt, because it is supposed to 
have become dirty ; but it should be taken out, and clean 
tallow put in its place. The tallow, after being taken out, 
need not be thrown away ; let it be melted, and any dirt 
that is in contact will fall to the bottom of the kettle. 
Again, if the engines are kept bright while in harbor, let 
the bright work, when about to proceed to sea, be coated 



236 DUTIES TO ENGINE ON AEEITING IN HAEBOR. 

over with melted tallow mixed with white-lead, which will 
resist the corroding influence of the salt water. On arrival 
in port, all that will be necessary is, to wipe of the 'tallow 
and white-lead, and the former bright appearance will be 
estored. 

277. Lubricators to he Examined. 

Occasionally, on arriving in port, the lubricators should 
be scalded out with hot water, to remove whatever dirt 
may have accumulated about them ; the necessity for this 
will depend much on the purity of the oil used. If fitted 
with Barton's lubricators, a new worsted should be put in 
at the end of every voyage, for it is apt to become gummy 
after a time, which prevents the capillary action from 
going on. 

278. Bearings to he examined. 

When the bearings of the engines are taken apart to be 
cleaned and examined, it is at times found that the brasses 
are cut or scored, from some defect in the lubrication. Oil-* 
grooves in the under brasses appear to be bad, for in a 
short time they become full of dirt, which hardens and 
cuts the bearing : it may be as well to fill these up with 
soft metal. The only case in which oil-grooves appear to 
be of any service is, when cut across the top brass, to con- 
duct the oil, etc., to their extremity. 

The bearings should now and then be taken apart, but 
not oftener than necessary ; for detaching the parts of the 
engine is likely to be attended with mischief, since after 
so doing the engine will require re-adjusting; and if 
screwed down too tight, the bearings will heat, and when 
once hot it is troublesome to get them cool ; they may be 
an annoyance during the whole of the following voyage. 
Or, on the other hand, if not screwed down tight enough, 
there will be mischief from jar to the machinery. 

If the vessel be fitted with beam engines, the upper 
side-rod end bearings require great attention, the little 
motion there is at that point not being enough to produce 
a good surface, and the wear is all on the upper and lower 



HOLDING-DOWN- BOLTS. 237 

side of the bearing, which in time wears it oval. Of 
course, when time and circumstances admit, this oval must 
be altered into a rounded form again ; but where this can- 
not be done, from want of time and opportunity, great 
caution must be used in tightening up the bearing ; for if 
too tight, we shall have one oval surface working within 
another, and if very tight, the side-rods will break just 
under the strap or eye. Many side-rods have been broken 
in this way. 

279. Outer Bearings of Paddh-shafts. 
Oxidation goes on here to a great extent, from the ac- 
tion of the salt water on the brass and iron which are in 
contact in the bearing. They require to be in good order, 
and the oil-holes free. Two cases have occurred in the 
Navy in which the paddle-boxes have been set on fire from 
the heating of the outer bearing. In one instance a broken 
punch was found in the oil hole. 

280. Piston-glands, Keys, etc. 

The piston-glands of all engines, but more particularly 
of those with short connecting-rods (in which any derange- 
ment of the parallel motion is more likely to produce a 
transversal strain of the piston), should be kept as high as 
the motion will allow ; for the more packing there is, that 
is to say, the deeper the stuffing-box (which is produced 
by keeping up the gland), the better guide it will be to the 
piston, and the more it will tend to keep it in a straight 
line. ' , , 

281. Screwing down the " Holding -down BoltsP 

When the vessel comes into harbor, the holding-down 
bolts should be looked to now and then, and screwed down, 
if necessary, hefore the steam is down ; for gales of wind 
will tend to loosen the engines on their sleepers, and if the 
operation be not performed before the steam is got rid of, 
we may not be able to get at the bolts, from the position 
of the side-levers. In screwing down the bolts, they 



233 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

should be taken diagonally, and one nut should be screwed 
down as mucb as another ; for it is to be presumed that 
the engine will thus come into its place more accurately. 
On the other hand, if the bolts be screwed down on one 
side only, the engine will probably be out of square with 
the ship. In vessels that are built diagonally, and also' in 
iron vessels, great care and judgment are required in 
screwing down the holding-down bolts. And after a ves- 
sel has been ashore or in dock, the holding-down bolts 
should be examined carefully ; in the former case it is a 
common thing to find them broken. 

The stays of the engines ought to be slacked when the 
ship is docked, or when on shore ; for at such times the 
vessel will spread open from being relieved of the pres- 
sure of the water outside. 

282. Examining, repairing, and repacking Slides. 
A little reflection will convince any person that, if a flat 
surface be continually rubbed, the middle will become 
worn away more than the edges, and from being flat at 
first it wears into a concave surface. Let us bear this in 
mind, and examine the action of the packing on the back 
of the slide. The packing surrounds the back of the slide 
in the form of a ring ; and as the slide is continually mov- 
ing upwards and downwards, to allow the alternate in- 
gress and egress of the steam, the middle of the portion 
rubbed by the packing — that is to say, the middle of the 
upper and lower projecting surfaces at the back — will be- 
come hollow, and it will tell upon the working of the 
engine ; for if, when the slide be depressed or elevated, the 
packing be screwed up tight, it will be slack when the 
slide is in the middle of its path. Again, if it be screwed 
up when the slide is half-way down, it will jam when an 
attempt is made to raise or depress it. The latter case is 
not unlikely to produce accidents ; for if the slide be 
thrown out of gear when it is at the top or bottom of its 
stroke, and an order be given to go astern, the engineer 



EXAMINING SLIDES. 239 

will perhaps find it so jammed that lie will not be able 
readily to move it. When the slide is taken out to ex- 
amine it, therefore, a straight- edge, as long at least as thQ 
slide itself, should be brought into contact with the back 
of the slide lengthways, to see whether it be in contact 
with the upper and lower projecting portion of the back 
throughout the length. If it be found to be hollow, the 
projecting parts should be filed down, and it is as well to 
leave the backs slightly rounded up in the middle to allow 
for their wearing away. After the backs have been filed, 
they should be smoothed carefully to prevent the packing 
from being cut away. 

Having examined and made good the defect at the back, 
it may happen that the face and nozzles will require look- 
ing to. They are apt to get leaky from the alternate ex- 
pansion and contraction of the metal, and from not attend- 
ing to the packing with sufiicient care ; for if the slides 
are not kept in contact with the nozzles, steam will pass 
between the slide and the back-plate, and gradually cut a 
channel for itself, as water would down the face of a chalk- 
cliff. To get them steam-tight again, the slide must first 
be made true ; that is to say, its faces must be made flat. 
The slide-faces should then be covered over with red-lead 
and oil, and the slide should be put in its place : let it now 
be moved up and down the extent of its travel, and. at the 
same time kept hard against the plate ; we shall by these 
means, on taking off the slide, detect the projecting sur- 
faces of the nozzles. If the mischief have not gone very 
far, these projections must be scraped down, but if that 
cannot easily be done, the part must be filed away ; this 
can be performed at the upper port with a crank-handle 
file, and at the bottom port a long-handle file must be used, 
having another person below to keep the file in its place. 
When the surfaces are nearly true, the red-lead and oil 
must be put on proportionately thin, or the part requiring 
to be taken off will not be discovered. A sheet of tin or 
white paper is of great service to reflect light on those 
16 



*^40 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

parts that are obscured. After the faces are brouglit to 
coincide, the slide should be rubbed once or twice against 
its facing, having previously covered /)ver the surfaces 
with a little fine emery and oil. Much dependence cannot 
be placed on this latter plan for grinding the surfaces to- 
gether ; for large pieces of emery will rub hollow places 
in the facing, if continued long. 

In repacking slides, great care is to be taken in making 
the gaskets ; for if the slide have been at work for any 
considerable time, the space at the back, between the slide 
and its casing, must necessarily become larger than it was 
when new. ISTow the gasket must be made to accommo- 
date itself to this, that is to say, it must be thicker at the 
back than at the sides, or else the slide will leak. The 
ends of the gasket must be made to bear well against the 
nozzle, to prevent the passage of steam from the steam- 
side to the exhaust- side of the slide without entering the 
cylinder. Where cotton can be obtained, it is preferable 
to spun-yarn for packing, because it is more elastic and 
retains its elasticity much longer. Canvas also when made 
up into packing answers exceedingly well ; it is not de- 
stroyed so soon by heat as common packing. A similar 
remark applies to the trunnions of oscillating engines, 
which, being circular at first, wear oval, and therefore the 
packing will not fit if uniformly distributed around it.* 

Slides require to be examined now more frequently 
than formerly ; for since the introduction of tabular boil- 
ers, and generally of boilers having a confined steam-space, 
and limited at the water-line, priming goes on to a much 
greater extent than formerly; consequently dirt from the 
boiler is carried over with the steam, and deposits itself 
about the slide and its casing ; and from the heat of the 
engine it becomes baked on, which renders the slides hard 
to move, and injures the packing and slide-facing. 

i_ 

* In making up the gaskets, it will be found a good plan to rub 
the soft soap over the yarn before it is plaited up, to suspend the 
galvanic action that would be likely to be set up. 



PARALLEL MOTION. 241 

283. To find the Length of Stroke of an Engine, 
Put the engine at the top centre ; mark on a batten the 
distance of the cross-head above the cylinder-cover ; then pnt 
the engine at the bottom centre, and mark again the height 
of the cross-head above the cylinder-cover; the distance 
between these two marks is the exact stroke of the piston. 

284. To adjust the Parallel Motion of Marine Engines. 
1. Side-lever Engines. — If while watching the engine 
at sea we notice that the cross-head does not move in a 
vertical straight line, we know that there is something 
wrong in the parallel motion. This should be set to rights 
at the earliest opportunity after arriving in port. The 
difficulty we have to contend with is, first to find out 
where the error lies, and afterwards to correct it. To do 
this, we must first of all put the engine exactly at half- 
stroke; this can be done as follows: Having found the 
length of stroke as in the last article, bisect it, and make a 
mark on the piston-rod to correspond, and move the en- 
gine round till the cross head comes to the point of bisec- 
tion, when the engine will be at half-stroke. This being 
accomplished, let us narrowly examine the parallel motion. 

Let FOG represent 
the half side-lever, 
the main centre, D F 
the cylinder side- 
lod, B Cthe parallel- 
motion side-rod, GB 
the parallel-motion 
bar, A B the radius - 
bar. Now the en- 
gine being at half- 
stroke, let us examine first whether the three points 
G, A, and B, are in one straight line.* Next, let 
us carefully measure G B and F C, also F G and B C, to 

* They are purposely put out of a line in the figure, to allow the 
line A B to be seen. 




242 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

ascertain wHether Gr F B C is a parallelogram, wliicli will 
be the case if G B = F C and F G = B C. If these con- 
ditions are not fulfilled, we must satisfy them by interpos- 
ing liners at proper places according to our judgment. But 
we must be careful about the point F ; for by interposing 
a liner there we should elevate the piston, and might en- 
danger its striking the top of the cylinder. If, however, 
these necessary conditions be fulfilled, and yet the motion 
is not true, we are sure it must be that the radius-bar 
A B is not of the proper length. Those who are in the 
habit of making calculations can discover whether this is 

1 . ^ 1 CO BC.FO 
the case or not by the formula Xb'^ CO DF ~ ^ (^^® 

Chapter III. p. 99). To effect this, multiply together B C 
and F 0, also C and J) F ; divide the former by the 
latter, and take 1 from the quotient. Then divide C by 
this result, and the quotient will give the length A B of 
the radius-bar. Those who are not conversant with such 
investigations must move round the engine till it comes to 
the top and bottom centres ; and if it be discovered that 
in so doing the point D moves to the left, the radius-bar 
A B is too short ; if, on the contrary, the point D goes to 
the right, it is too long. Some engines are so fitted 
that the point A can be shifted to the right or left, and 
then by means of liners we can alter the length at our 
discretion. Some, however, are not fitted in this way ; and 
if any difficulty present itself about the adjustment, the 
best plan is (supposing the piston-rod to be vertical at the 
middle of the stroke) to endeavor to correct it when at the 
bottom, and let it take its chance at the top ; for any defect 
there will not be of such consequence as in other positions, 
because nearly the whole extent of the piston-rod being 
outside the cylinder, allows for a little play without Jiaving 
much effect on the stuffing-box; whereas if any defect 
existed uncorrected when the piston cross-head is down, 
the strain is brought on the stuffing-box, and then by 
reaction on the radius-shaft plomer-block. Engineers are 



PARALLEL MOTION. 243 

at times satisfied witti ascertaining that the three points 
before mentioned, G, A, B, are in the same horizontal line 
when the engine is at half-stroke ; but this evidently will 
not tell us whether the radius-bar A B, or the parallel-bar 
G; B, is too short or too long, which is clearly an important 
thing to ascertain. 

Many engines have their parallel motions thrown out 
of adjustment in the following way : The piston perhaps 
strikes the bottom of the cylinder, because the lower brasses 
of the side-rod and connecting-rod have worn away: to 
prevent this, a liner is put under the lower end of the side- 
rod to raise the piston in the cylinder ; by doing which 
we throw the parallel motion out of adjustment, because 
the radius- shaft ought to have been raised at the same 
time as well as the parallel-motion side-rod. A somewhat 
similar effect will take place if a liner be put under the 
lower connecting-rod brass. The better way is to line up 
the brasses of the upper end of the side-rods, and by this 
method we shall not affect the parallel motion.* We 
must take into consideration that the wear on the brasses 
of the cylinder side-rods is much greater than on the mo- 
tion side-rods ; for they have the whole press are on the 
piston to contend against, whereas the duty of the others 
is merely the guidance of the piston-rods, so that we shall 
not have to line up the one so much as the other. 

2. Pakallel Motion of the Gokgon Engines. — The 
first thing we have to look to is the wearing away of the 
brasses of the rocking standard, so that when the engine 
is at half-stroke the radius-bar and rocking beam centres 
are not in a straight line. If we examine this kind of 
engine, we shall readily be convinced that the parallel 
motion is very liable to get out of order. For the con- 
necting-rod brasses, by wearing away, raise the piston and 
cross-head, and at the same time the rocking-standard is 

* That is to say, if the parallel motion be that usually known by 
the name of Maudslay and Field's ; but if it be that known as Boult^^n 
and Watt's, lining up either end of the side-rods will throw it ofxk 



244 DUTIES TO ENGINE ON ARKIVING IN HARBOR. 



wearing down. It is true tlie shaft-brasses are wearing 
also, but tbej will be found not to wear so fast as the 
brasses of the connecting-rod. 

With engines of this kind we must carefully examine 
the parallel motion after the entablature has been meddled 
with. For instance, if the woodwork to which the entab- 
lature has been secured shrink, and the entablature be 
screwed up, and it be screwed up more on the one side 
than on the other, we shall twist the parallel motion, by 
shifting the fixed point of the radius-bar without altering 
the position of the cylinder. 

The proportion to be preserved among the lengths of 
the several parts will be found in the Appendix. 

285. To ascertain geometrically the Length for the Radius-har 
in Side-lever Engines. 

Let F be the 
half side-lever, F D 
the side-rod, C B the 
parallel-motion side- 
rod, and B G the 
parallel-motion bar. 
Let the side-lever 
O F come into the 
positions OFj and 
Fg when at the 
extremes of the 
stroke, the point F 
having described the 
arc Fj F F„ and C 
having described the 
arc Cj C Cg. Join 
Fj Fj, and bisect 
the versine in the 
point o; through o 
draw D at right 
angles to OF, which 

will contain the point D. Again, let Fj be the 




TO ADJUST PADDLE-SHAFTS. 245 

position of F when at tlie extreme of tlie stroke, the crank 
being at tlie bottom centre. On o D produced set off Dj, 
making F^D, = F D ; tben Dj is the position of the top of 
the piston-rod when the piston is at the top of its stroke. 
From C, draw a line parallel to F,Dj, and make B^Cj 
equal to B C. Again, by the same process find the points 
Cj, Fj, D„ and B«, corresponding to the positions which 
C, F, D, and B will have when the piston is at the bottom 
of the stroke. Then the extremity of the radius-bar has 
during the whole motion come into the three positions 
Bj, B, and B^, and the centre of the circle passing through 
these points will be the fixed point of the radius-bar. Let 
A be this point, and the length of the radius-bar will be 
AB. 

286. To get the Paddle-shafts into the same Straight Line. 

The weight of the paddle-shafts and wheels has a ten- 
dency to make them droop bodily by wearing away the 
brasses; and, in addition to this, they are liable to turn 
through an angle, because the pressure is always forcing 
the paddle towards the head of the ship. We will first 
endeavor to detect whether the paddle-shaft has drooped 
or not. To do this, place the cranks first of all on the top 
centre ; then take a gauge, of any convenient length, but 
shorter than the distance between the centre of the shaft 
and boss of the crank, and made of the form repre- 
sented by the figure. Let the point a be placed in 
the centre of the intermediate shaft, and with the 
end b describe a portion of a circle on the face of 
the opposite crank, having previously chalked it over 
so as to see the mark made. Let now the cranks be turned 
through a quadrant of the circle, and make another mark ; 
turn them round to the bottom centre, and make a third 
mark ; finally, turn it through another quadrant, and make 
a fourth mark. Now the order in which these marks in- 
tersect each other must be noticed ; and it is clear that if 
the centre of the paddle-shaft is in the same line as the 



I 



246 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

centre of the intermediate shaft, these four marks on the 
face of the crank will coincide ; but if the first mark be 
at a greater distance from the centre of the paddle-shaft 
than the third mark, then the paddle-shaft has gone bodily 
down. The same reasoning with the second and fourth 
marks will tell whether the shaft has come bodily forward. 
We have next to examine the outer end ; this end is 
liable to droop, from the weight of the paddle, and like- 
wise to be forced forwards, from the pressure. The way 
to discover if that be the case is as follows : Let the cranks, 
as before, be placed on the top centre. Let C A, A B be 




the position of the intermediate shaft and its crank, and 
E F and D B that of the paddle-shaft and its crank, the 
end F having drooped through the space F F', which it is 
our object to find. Measure the distance B D, between the 
faces of the two cranks, in a line with the crank-pin. Care 
should be taken, at the same time, that the shaft does not 
move endways: in turning round, the ends of the shaft 
should be gauged, as a test of this. Then turn the engine 
through two quadrants, till the cranks come to the bottom 
centre, and measure the space G H, the distance between 
the faces of the cranks in this position. If B D = G H, it 
is a proof that the shafts C A and E F are in the same 
straight line ; but if B D be greater than G H, it is a sign 
that the end F is too low. Turning the brasses end for 
end will sometimes rectify the defect caused by the for- 
ward wearing awa}^ of the shaft-brasses, and snifting the 



PADDLE SHAFTS. 247 

top and bottom brasses will at times correct tlie error in- 
troduced bj the drooping ; but if tbe error be considera- 
ble, the brasses must be lined up, or packing pieces intro- 
duced under the plomer-blocks. 

To allow for the probable drooping of the paddle-end 
of the shaft, the end of the crank-pin is made to fit loose 
in the eye of the paddle-crank. This object was formerly- 
gained by the use of the drag-link. The drag-link was a 
coupling-piece to connect the two crank-pins together, one 
crank being in advance of the other. 

The rule by which we get the thickness of the piece to 
be interposed at F is given below. From the measured 
distance B D, take the measured distance G H, and divide 
the remainder by two. Then multiply this result by the 
length of the paddle-shaft (from the crank to the outer 
^ bearing), and divide by the length of the crank ; the quo- 
tient, is the distance FF' required.* If the paddle-shaft 
be wholly below the intermediate shaft, this error should 

* Let D'H' be the position D H would assume if F E were in the 

same straight line with A B ; .-. D'H' is parallel to" B G, and D D' = 

HH',andG:^' = B'D'. 

Also since GrH'=rGH + HH' 

and BD'=:=BD — DD' - 

and because H H' = D D' 

GH-f HH' = BD — DD' = BD — HH' 

Hence 2HH' = BD — GH 

BD-GH 
or HH' = 

Z 

Again, by similar triangles, 

FF_DD'_HS' 

FE""DE ""HE" 

_^, FE „^, FE BD — GH 

or FF= — .HH= — 

BE BE- 2 

Example.~Let F E = 12 ft. 6 in. ; DE = 1 ft. 9 in. ; B B = 7 in. ; 

andGH = 6|in. Then BD — GH = | in. 

^^, 12-5 1 12-5 

FF' = — X— = 

1-75 16 28 

which is rather less than half an inch. Hence, if the thickness of 

half an inch be interposed, the defect will be fully compensated. 



248 DUTIES TO ENGINE ON AERIVING IN HARBOR. 

be corrected first. It will be seen that similar methods 
will apply to tbe shafting of screw-engines. 

287. To set the Slides of the Engines; that is to say, to put 
the Stops on the intermediate Shaft. 

Throughout this work we suppose that the engine is 
rightly constructed and sent out of hand by the engine- 
maker ; and consequently we must take for granted that 
the eccentric-rod; gab-lever, valve-lifter, slide-rod, etc., are 
of the proper length and position when the engines are 
new. But it becomes the duty of the engineer to shift or 
alter the position of the stops on the eccentrics from time 
to time, as these parts are liable to wear, and a little altera- 
tion in their position or size affects materially the lead of 
the slide. We must bear in mind that we are here deal- 
ing with a part of the engine where an error of one-eighth 
of an inch will double or annihilate altogether the lead of 
the slide. 

In setting the slides we must first of all put the crank 
on its centre. Let us suppose that we wish to set the slide 
correctly for the upper port ; to do this we must get the 
piston at the top of its stroke, and consequently, in a beam- 
engine, we must get the crank on its bottom centre, or if a 
direct engine, on its top centre. Now this we accomplish 
-as follows : If the ship be on an even keel, and the engine 
square with the ship, or in other words, if a line at right 
angles to the keel be parallel to the piston-rod, then find, 
first, the diameter of the crank-pin, and take half of it for 
a radius ; with this radius describe a circle round th^t end 
of the shaft to which the crank is affixed, having before- 
hand chalked over the surface, to render the circle con- 
spicuous ; this having been done, take a plumb-line, or one 
of the engine-nuts fastened to a piece of twine, and place 
the line in contact with the inner surface of the crank, 
and let the crank be moved round till the line is in con- 
tact with the circle described and the crank-pin at the 
same time. When this takes place the engine is on its 



TO SET THE SLIDES. 249 

centre, tlie crank being vertical. The probability, how- 
ever, is, that the vessel will not be on an even keel ; we 
must consequently have some way of effecting our purpose 
independently of the plumb-line. Let the circle be de- 
scribed, as before, round the centre of the shaft ; next get 
two battens whose edges have been made quite true, and 
let them be connected together, so as to be at right angles 
to each other ;* then, if the engine be a beam-engine, let one 
edge of the square be applied to the flange of the air-pump, 
the air-pump cover having been removed, and the other 
edge be brought into contact with the pin of the crank ; 
we must examine whether it is in contact also with the 
edge of the circle previously described; if not, let the 
crank be moved round as before, till a contact takes place. 
A moment's reflection will show that when this happens 
the engine is on its centre. If the vessel be fitted with 
direct engines, we must use the flange of the cylinder in- 
stead of that of the air-pump. We should not be certain 
of getting a true result if we were to apply the square to 
the upper surface of the air-pump or cylinder-cover, instead 
of taking it off and applying it to the flange, because the 
cover may not be so true as the flange, if the joint be 
thicker at any one part, the flange being of necessity planed 

* To get two Battens at right angles to each other. 

Measure off, on a board, 17 inches in length, then open a two-foot 
rule, and extend it as if it were a pair of compasses, till one end is in 
contact with one extremity of the line, and the other end with the 
other extremity ; the rule will then have its two legs very nearly at 
right angles with each other ; for each side of the rule being 12 
inches, the base of the triangle thus formed will be [Euclid, Book I., 
Prop. 47) v^l22+T22 = v/288 =16-97 = 17 inches nearly. 

Otherwise, measure off a line 5 inches long, and let the marks cor- 
responding to 3 inches on one \Qg of the rule, and 4 inches on the 
other, be brought into contact with its two. extremities ; the legs of 
the rule will then be at right angles ; for 3^ 4- 42 = 9 -f 16 = 25 = 5^ : 
the included angle is a right angle. 

The same rule will hold if a line 10 inches in length be measured, 
and the lengths 6 and 8 inclies be brought in contact with its ex- 



250 DUTIES TO ENGINE ON AKEIVING IN HARBOE. 

truly, for tlie piirpose of getting the engine true ; or we 
may get tlie extreme of tHe stroke by turning tlie cranks 
oyer tlie dead spaces at the top and bottom of the stroke, 
and making a mark at the extreme top and bottom on the 
piston. 

After we are satisfied with the placing of the crank, let 
the slide be put in its place, so as to give the proper 
amount of " lead" at the upper port ; the eccentric must 
next be moved round till the eccentric-rod falls into gear ; 
then place the stop on the shaft in close contact with that 
on the eccentric. The crank must next be placed on the 
top centre, and the slide moved with the engine, so that 
it may be ascertained whether there is the proper amount 
of lead for the lower port. If less than the proper quan- 
tity, it must be increased by lengthening the slide-rod, 
and thus compromising the lead to some extent at the 
npper port, for the sake of giving more to the lower."^ To 
adjust the stops for the reverse motion, let the eccentric- 
rod be disconnected from the gab-lever pin, and let the 
eccentric be moved round the back way, without the en- 
gine, till the rod again falls into gear. ISTow place the 
stop for the back way, and let the slide be examined at 
both ports by turning the engine, eccentric, and all, to see 
whether there is the proper amount of lead for the reverse 
motion at the two ports. If the engines be beam-engines, 
there is usually the same amount of lead (about J- of an 
inch) allowed at the top and bottom port ; but more lead 
is required at the lower than at the upper port with direct 
engines ; this can easily be obtained by lengthening the 
slide-rod when necessary ; with engines of this latter class, 
it is usual to allow about ^ of an inch, or more, of lead 
below, and about j\ or less above the piston ; thus the in- 
crease of momentum on the down-stroke, arising from the 
weight of the piston, etc., is overcome, and the change of 
motion from the down to the up-stroke is effected without 

*The same thing may be accomplished by shortening or lengthen- 
ing the eccentric-rod, if considered advisable by the engineer. 



TO SET THE SLIDES. 251 

any violent jar to the machinery. We shall thus increase 
also the lead on the exhanst-side at the upper port, which 
is likewise an advantage in unbalanced engines. The 
actual amount of lead depends on the velocity with which 
the wheels are revolving. In locomotive engines, and all 
that move at high velocities, the lead must be considerable, 
in consequence of the great speed of the piston ; the steam 
would be ineffective in checking the momentum, were it 
to enter at so late a period in these engines as in the 
marine engines. *ro take the opposite extreme, if we turn 
round the engine by hand, we want no power to check the 
momentum, because the piston is moving so slowly ; and 
therefore the slower the piston travels, the less the amount 
of lead required. The lead of which we have hitherto 
spoken is called the lead on the steam- side, but most en- 
gines have another kind of lead ; in them a communication 
is made with the condenser before the piston has completed 
its stroke, so that on what is called the steam-side of the 
piston there are three processes successively employed : 1. 
The influx of the steam; 2. The steam is cut off, and 
works by expansion ; and 8. Before the stroke is terminated 
the steam is allowed a passage to the condenser. This 
latter will of course materially assist us in checking the 
momentum of the piston, for it is not only checked actively 
by coming into contact with fresh steam, but the force of 
that on the side where it was impelled is taken away. The 
lead is then said to be on the exhaust-side, and it is effected 
by taking off from the^ upper and lower edge of the slide ; 
so that when one of the ports is open, the amount of lead 
required for the steam, the other port shall at the same 
time be open a little to the exhaust. In Maudslay's direct- 
action engines, there is considerable lead on the exhaust- 
side at the upper port, for the same reason that there is 
more lead on the steam-side at the lower port, viz., to im- 
prove the working of the engine. 

We have hitherto supposed that the engines are new, or 
have had a thorough repair ; but if the engines have been 



252 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

at work for three or four years, and it becomes necessary 
to set tlie slides, the slide-rod and eccentric-rod must be 
readjusted ; because, since the brasses of the weigh-shaft 
and slide-rod are subject to continual friction, and therefore 
liable to wear, it will have the effect of depressing the slide, 
and so give us more than the due amount of lead at the 
lower port, by taking away the same quantity from the 
upper port. The brasses of the eccentric-ring are likewise 
continually wearing, which has the effect of virtually short- 
ening the eccentric-rod. ]^ow this will cause the slide to 
be elevated or depressed, according to the manner in which 
the gab-lever is placed on the weigh-shaft.* This latter 
defect may therefore exaggerate the former defect, or help 
to counteract it, according to the nature of the engine. 
"We must also notice the wear of the gab and gab-lever 
pin; the continual jar on them as the slide-stroke is re- 
versed produces great wear, unless they be well case- 
hardened, and even then it will frequently happen that one 
side of the pin may be much better hardened than the 
other, and the softer side will become most worn, and on 
the return of the stroke there will occur what is technically 
called back-lash ; that is to say, the eccentric will be in 
motion some little time without acting on the slide. It is 
manifest that unless these defects of the engine be corrected, 
or made to compensate each other, it will be useless to 
attempt giving the requisite amount of lead, because an 
error in the motion of the slide of yV of an inch will be a 
serious thing as far as regards its lead. We will therefore 
proceed to show the way of correcting and adjusting the 
length of the eccentric-rod ; to do which it will first be 
necessary to place the slide at the middle of its stroke. 

288. To place the Slick in the Middle of its Stroke. 
Take a batten and place it over the ports when the slide 
is out, and with a penknife mark off on the batten the 

* It will depress the slide if the gab-lever hang down, and elevate it 
if the gab-lever stand up. 



BEMARKS OX SLIDES. 253 

depths of the ports ; this will give us not only the depth 
of the port, but the distance between them ; let this be 
placed over the slide, so that the cover on the steam-side at 
top and bottom shall be equal, and we shall get the amount 
of steam cover that the slide has ; shall also ascertain if 
there be any cover or lap on the exhaust-side, and whether 
positive or negative. If the gab-lever is at right angles 
to the eccentric-rod^ when the slide is at half-stroke, and 
the amount of lead is the same at both ports, the laps on 
the steam-side must be equal to each other 

289. To adjust the Eccentric-rod. 
Place the slide in the middle of its stroke ; then let the 
throw of the eccentric be placed in a line with the eccen- 
tric-rod. Open a pair of compasses to any convenient 
distance, and placing one point in the centre of the gab- 
lever pin, with the other make a mark on the ecceutric- 
rod. Then let the eccentric be turned half round, so as to 
have the throw again placed in a line with the eccentric- 
rod; we see that by so doing the gab must have passed 
over the gab -lever pin. Take the compasses (opened to 
the same extent as before), and make a mark on the eccen- 
tric-rod on the other side of the gab-lever pin ; the centre 
of the gab should be the middle point between these two 
marks. If that be found not to be the case, the eccentric- 
rod must be altered accordingly. This is to be effected 
where the rod is connected to the band or ring by putting 
on a washer, or, on the other hand, by filing off the part 
of the bolt that screws up the ring. 

290. Remarhs on the Alteration of Slides. 
In speaking of the adjustment of slides, we have not said 
a word concerning any alterations to be made in the slide 
itself — such as by taking off some of the lap, or otherwise 
altering it ; and the reason of this is, that such an alteration 
should never be made without the knowledge and approval 
of the authorities who are responsible for the ship. We 



254: DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

must bear in mind tliat tlie slide is regulated by the capaci- 
ties of tbe boiler ; and tbat if any lap be taken oif with tbe 
view of allowing tbe steam to be admitted tbrougb a" 
greater portion of the stroke; the boiler might become ex- 
hausted, or it would require the fires to be urged in a 
wasteful manner to keep up the supply. It would be an 
improvement to take off a considerable portion, if not all, 
the lap from many engines driving paddle-wheels, if the 
engines are fitted with expansive gear, so that the steam 
can be cut off by expansion under ordinary circumstances 
by that gear ; and then the full power of the steam may be 
admitted at extraordinary times during the whole stroke, 
or nearly so. Because in paddle-wheel vessels the number 
of revolutions is sensibly diminished from any cause pro- 
ducing greater resistance ; as, for instance, against opposing 
wind and sea, or when towing; and when this happens, 
although the boiler generates its usual quantity of steam, 
it cannot enter the cylinder, and consequently escapes by 
the safety-valve. Since the lap on the slide gives it the 
character of permanent expansive gear, this cannot be 
remedied at the time ; but if, on the other hand, we had 
been working on one of the grades of the expansive 
gear, it could have been detached ; and if there were no 
fixed lap on the slide, the steam would enter the cylinder 
instead of being lost in the atmosphere. There are many 
cases in which the additional work thus to be obtained 
would extricate a ship from a perilous position ; yet still 
no engineer or commanding-officer would be authorized 
thus to tamper with the slides without the sanction of his 
employers, whether it be the Admiralty or the Company 
to which the vessel belongs. 

When lap is taken away from the steam-side of the slide, 
some portion of the face should also be taken away from 
the exhaust-side, otherwise the uncondensed steam would 
produce too much effect in checking the motion of the 
piston. And it must be remembered that, when any altera- 
tion is made in the slide-face, whether it be reduced or 



SC:^LING BOILERS. 255 

added to, tlie driving-stops on the intermediate shaft must 
be altered also. If the lap is increased, the stops must be 
advanced ; and if decreased, they must be put back. 

291. On Cleaning out and Scaling the Boiler. 

It is sometimes found to be difficult to get the scale out 
from the bottom of a boiler, because there is so little space 
under the flues and fireplaces, and a rake cannot be em- 
ployed to extract it; this will be found particularly to be 
the case in the angles or corners of the boiler, for the rake 
will only jam it up into them. Some boilers will not admit 
a man underneath the flues and fireplaces to get the scale 
out ; and yet we must be particular in seeing that the boiler 
is quite clean ; for any scale that may remain keeps the 
heat away from the water, and injures the plate, and serves 
as a nucleus for any other deposit. The best instrument 
to use is a slice ; this can be forced under the mass, and 
bring it away by portions ; and should any parts of it 
hang about the water-ways, they should be sliced down 
and hauled out from the mud-hole. Moreover, it is diffi- 
cult to get out the stuff in consequence of the interference 
of the stays supporting the fireplaces and flues above the 
bottom of the boiler. This difficulty exists more in flue 
than in tubular boilers. Our great object is not to allow 
any scale to remain in the boiler to form a nucleus. 

After a boiler has been cleaned out, the blow-out cocks 
should be carefully examined, and the passages leading to 
them : for if the pipe go in a direct manner through the 
bottom of the boiler, the scale taken from the boiler is apt 
to get into the pipe and choke it; the blow-out cocks 
should be opened to let the water force it out ; this should 
be done before the man-hole door is on, to make sure that 
they are clear. This seems to be the proper place to call 
attention to the fact of the blow-out pipes choking when a 
vessel is at anchor in a roadstead, or any other place where 
she is rolling. If there be ever so little scale in the boilers, 
it will find its way into the blow-out pipe. This will take 
17 



4. 
256 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

place when the boilers are what is called empty ; that is, 
when there is merely a little water remaining after the 
boilers are blown out, and washing about from side to side, 

and drifting portions of scale with it. When the 

was employed on the north coast of Spain, and at anchor 
in Sebastian Bay, where there is more or less swell setting 
in, it was a common thing to find the blow-out pipe of the 
front boiler choked ; but as there were pipes to the after 
boiler, and circulating ^ipes fitted, the front boiler could 
be filled from the others, for the four boilers constituted 
but one in four pieces ; quite a hard mass was at times ex- 
tracted from the pipe, the heat having had the effect of 
solidifying it. To prevent the scale working into the pipe, 
the boiler should be pumped dry. If this cannot be done, 
the mud-hole doors must be taken off to empty the boiler 
thoroughly. A coarse grating ought to be fitted over the ' 
pipe, and thus large pieces of scale would be prevented 
from entering the pipe. This can be made in the following 
way : Two strips of iron should be placed at right angles 
to each other, and bent over to form a hemisphere, with 
a bolt screwed into the top ; these can be placed over the 
blow-out pipe, and the bolt unscrewed, so as to bring the 
head of the bolt hard against the under part of the flue or 
fireplace, for the sake of keeping it in its place. In the 
figure, A A is the bottom of 'the fireplace or flue, B the 
gMH^M|^Hgnn||^^^ blow-out pipe, C C the bottom 

of the boiler, E E one of the 
strips of iron forming the 
grating, D the screw-bolt. 
Now if E E have a greater 
span than the blow-out pipe, 
that its shoulders may rest 
on the bottom of the boiler, it is clear that if we bring the 
head of the bolt against A A, E E will be pressed down, 
and secured over the pipe. The strips should evidently be 
made of the same metal as the boiler, for fear of a galvanic 
action being set up. Copper was employed in one vessel 




STOPPING CRACKS IN BOILERS. 257 

fitted with an iron boiler, and after a time tlie pipe broke 
away from tbe boiler. On examination, tbe pipe appeared 
so soft tbat it could be cut with a knife ; the iron had been 
converted into plumbago. 

292. Bust- Joints. 
This kind of joints is made by mixing together cast-iron 
borings, sal-ammoniac, and sulphur ; it is then caulked into 
the joints, and when dry becomes a hard mass, perfectly 
steam and air-tight. 

293. Stopping Cracks in Boilers, and repairing Tubes. 
Cracks generally arise from blisters, which are usually 
caused by imperfect union of the iron when rolled. "When 
a crack is discovered in the flue of a boiler, it may fre- 
quently be prevented from extending farther by drilling a 
hole at each extremity of the crack, and putting in a rivet. 
If the crack be of any considerable length, let more rivets 
be put in, and well riveted down ; this will prevent the 
crack from spreading, and when caulked, will generally 
put a stop to the leakage ; but if the caulking be found 
inefficient, let some lead be driven in and caulked. "Wood 
may also be used as a temporary expedient to stop leaks 
in boilers. In patching a boiler, the piece cut out should 
not have angular corners ; for if there are such, it will be 
found that the plate will crack at the angular points. The 
patch ought to be put on in the inside of the boiler, to 
prevent its becoming over-heated."^ 

* We have recommended in p. 230 that leaky tubes should be 
plugged up at their ends with wood. This is only a temporary ex- 
pedient ; a more permanent repair will be to get a smaller tube from 
some other vessel or dockyard, and place it inside the leaky one, 
setting on the ends with a conicakmandril to render it water-tight. 
This goes on the supposition that all the spare tubes of the vessel 
are used up, and that no other of the same size can be obtained. 



258 DUTIES TO ENGI^^E ON ARKIVING IN HARBOR. 

294. Repairing the Fire-hridges and Ash-pits. 
Should it become necessary to repair tlie fire-bridges 
at any time wben in barbor, great care sbonld be taken, 
when made of iron, if a patch be pnt on the top, that the 
piece put. on be not hollowed out below, so as to prevent 
the free escape of steam ; that is to say, it should not be 
convexed upwards. Otherwise, the flame acting on the 
patch converts the water beneath it into steam, which has 
a tendency to rise, and instead of ascending to the surface 
of the water, becomes locked (as it is generally termed) in 
the hollow ; and, as we know, steam, like all gases, is a 
non-conductor of heat (see p. 25), consequently the iron 
becomes over-heated, and burns. Fire-bridges have given 
much trouble when this has not been attended to. In a 
well-constructed fire-bridge that has a good incline, there 
is no difiSculty; for the steam having free egress, the 
bridge is preserved. The same remarks hold good re- 
specting repairs to the bottoms of ash-pits; the patch or 
plate, indeed, should present a rather concave appearance 
to one looking down on it. If made quite flat at first, 
the hot ashes being on the upper side and the water below, 
the upper surface will always be hotter than the lower, 
and the effect of the heat will therefore be to expand the 
upper surface more than the lower, and consequently it 
will shortly present a convex appearance within the ash- 
pit ; or, speaking technically, will huckle towards the fire. 
Hence round-bottomed ash-pits are to be preferred to 
others. Messrs. Boulton and "Watt used to make the 
water-ways of their boilers wider at the top than at the 
bottom, to give a free upward motion to the steam. 

295. Staying the Boilers. 
In old boilers, stays were interposed between the top 
of the fireplaces or flues to support the shell, and they 
were curved a little, like a very elongated S, so that if 
exhaustion take place at any time in the boiler, and the 
reverse-valve did not act, they would spring, and the 



J^ 



BOILER WATER-GLASS. 259 

cliance of injury to tlie crowns of the fireplaces or flues 
was diminislied. This hardly affected the tension of the 
stay so far as the outward pressure was concerned ; for if 
only slightly bent, it would require an enormous strain 
lengthways to straighten it. Of late years tops of boilers 
have been stayed from the bottom, and not from the 
crowns, of the fireplaces, and the stays are straight. 

296. Increasing the Load on the Safety-valve. 
If it be deemed advisable to increase the load on the 
safety-valve, it will be necessary to increase in the same 
ratio the weights on the escape-valves of the cylinders and 
the overflow-valves of the feed-pumps. In some cases the 
weights are of iron ; and, as space is sometimes an object, 
it may be as well to ascertain whether the same object 
may not be gained by substituting a leaden for an iron 
weight. 

297. Boiler Water-glass. 
It is often found in new vessels, that the water in the 
gauge-glasses is unsteady. This arises from the high state 
of ebullition of the water in the neighborhood of the 
lower end of the gauge-glass, which causes a mixture of 
steam and water to be found at times in the glass, and the 
water-level is uncertain. When this happens, an attempt 
should be made when in harbor to remedy it. This can 
generally be done by leading up a pipe from the upper 
end into that part of the boiler where the steam is purer, 
and also conducting another pipe from the lower end to- 
wards the bottom of the boiler into the more solid water. 
It should not, therefore, terminate over the top of the fire- 
places, where the heat is great and the ebullition strong. 
Gauge-glasses and gauge-cocks should always be placed 
as nearly as possible directly over the keel, where they 
will be least influenced by the rolling motion. The pitch- 
ing and 'scending motion is but of little consequence, the 
length of the boiler bearing such a small proportion to 



260 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

the length of the ship that the water will not rise or fall 
much on that account. 

The gauge-glass should always be placed in that part 
of the boiler which is in a plane dX right angles to the 
keel, to prevent an inconvenience arising from the roll- 
ing of the ship. 

298. Internal Feed-pi;pe. 
Let the internal feed-pipe be examined, to ascertain 
whether it is sufficiently under water ; otherwise the steam 
will be apt to get into it, and cause the boiler to feed 
badly, and make a sharp, cracking noise in the pipe, if 
the valves of the feed-pump are not tight. The fe*ed- water 
should not be discharged near the surface of the water, 
because it checks the ebullition. K the pipe do not go 
far down, it will be a great annoyance to the engineer, 
when connected with boilers that are apt to prime. 

299. The Steam-gauge to he examined occasionally. 
The steam-gauge should be taken off occasionally, 
when in harbor, and cleaned out ; for the water is apt to 
get into it, and render it an incorrect indicator of the 
steam-pressure. The leg attached to the boiler will oxi- 
date, and therefore from wasting the bore will increase, so 
that a depression of one inch in that leg will cause more 
than an elevation of one inch in the other. Therefore, if 
the rod had risen one inch, the difference of level will be 
less than two inches, and consequently the real pressure in 
the boiler will be less than the indicated pressure as shown 
by the gauge.* 

800. Replacing the Fire-hars. 
When putting the fire-bars in a boiler, the side ones 
should be placed close alongside the fire-place, that the 
fire may not be too brisk between it and the iron plate, 

* Thus, let the radius of the bore when new be r, and let the 
radius of the leg in contact with the boiler become r' by oxidation ; 



SWEEPING FUNNEL, ETC. 261 

least it get over-heated and the water be driven away to 
the other side, when the plate will crack and the boiler be- 
come leaky ; this is more particularly to be attended to 
when using "Welsh coal, from the intense heat given out in 
the fireplaces ; whereas, with more bituminous coal, the 
heat is given out in the tubes or flues to a greater extent. 

801. Sweeping the Funnel, and the attention requisite to he 
paid to it. 
When the tubes are swept, it is at times necessary to 
clean the funnel ; this necessity does not arise generally be- 
cause of any fear of the draught becoming lessened ; for a 
considerable quantity of soot lodged in the funnel would 
have but little influence : but if allowed to stay there, and 
the vessel remain at anchorage any considerable time, 
especially if it rain, and the funnel be not covered over, 

and suppose the mercury to fall through the space x when it rises 
one inch in the other leg. 

rtr'^x = 7tr*.l 
or r'* x=r* 

rt 
»=^ 



a;-f-l_r* + ^'* 
' 2 "■ 2/2 » 

But a? -f 1 is the difference in level caused by the rise of 1 inch in 
cc-fl 
the index, and . • . — ^ — = the number of pounds pressure in the 

steam corresponding to the rise of 1 inch. Hence, when the pointer 







Example.- 


-Letr= -, and r =-+- = -- 




r« + r'' 4^256 64+81 145 




2r'' „ 81 162 162~°"'- 
2X256 



262 DUTIES TO ENGINE ON AKRIVING IN HARBOR. 

the wet will loosen the hard crust of the soot, and the first 
time the fires are lighted, the vibration of the boiler will 
detach it, and cause it to fall about the deck ; so that it 
will be essential to get rid of it while the vessel is in har- 
bor. If much time cannot be spared, the greater portion 
of the soot may be removed by firing a pistol or musket 
up ;^ the vibration caused by this is sufficient to shake off 
that which would otherwise become loose. But if time 
permit, the better plan is to sweep the funnel in the same 
manner as the flues. The furyiel should likewise be kept 
well tarred over on the outside, for the sake of preserving 
it. Coal-tar is mostly used ; this looks well ; but it is neces- 
sary to repeat it often, nor does it protect the funnel for 
any length of time. Stockholm or vegetable tar, mixed 
with a small portion of turpentine, will be found a much 
better material ; it will preserve the funnel better, and last 
much longer. Hot salt water is sometimes mixed with the 
tar instead of turpentine ; but this probably renders the 
funnel more susceptible of rust. When first coated over 
with Stockholm tar, the color is bad ; but as it dries it 
turns to a good black color. A good mixture may be ob- 
tained by using Stockholm tar combined with an equal 
quantity of mineral tar. In harbor a canvas funnel-top is 
used to prevent the rain from running down the funnel 
and oxidizing the uptake and smoke-box, etc. ; or, which 
is still better, an iron top, the edge of which is made to 
overhang, and is raised a few inches, to allow egress for 
the smoke when fires are lighted to preserve the boilers. 

802. Goal-Bunkers to he examined. 
If lined with copper, it will sometimes be found that the 
ends of the stays which are screwed or driven into the 
ship's side wiU be eaten away by galvanic action. The 
bunkers of a ship have been known to give way from this 
cause ; so much so as to cause apprehensions that the whole 

* Care should be taken that blazing soot do not fall down on the 
band. 



EEMOVING TOOLS AND RUBBISH. 263 

contents of them would be discliarged into the engine-room. 
The system of cross-stays is objectionable for this reason, 
and likewise because they are likely to be bent and drawn 
when struck by large masses of coal. Angle-iron has been 
found sufficiently strong and much more suitable; this 
would of course be riveted up and down the inside of the 
coal-bunkers. Whenever the weather permits, the coal- 
box plates should be taken off, to allow the gas that is 
evolved from the coal to pass off through the gratings. 
The gas alluded to is chiefly carburetted hydrogen, the 
fire-damp of our mines, and the gas commonly burnt in 
our shops, etc. 

803. Coaling Ship. 

The coal remaining in the bunkers should be trimmed 
towards the doors, or at all events levelled, to be used 
first ; for coals that have been long in the ' bunkers lose 
much of their value, owing to the high temperature of the 
place in which they are confined. The fresh coal should 
be received as dry as possible. Welsh coal takes up less 
room than north-country coal. In voyages of consider- 
able length, it would be advisable, where it can be man- 
aged, to have a mixture of the above coals : steam will be 
got up more speedily, and less wood will be required; 
whereas if none but Welsh coal is used, much wood will 
be required for lighting fires. Again, with this mixture 
the fires can be worked thin. For surveying- vessels, and 
others in which stoppages are frequent, north-country coal 
is best, because in pushing the fire backwards and bring- 
ing them forwards so many ashes are not made. With 
tubular boilers, in which an accumulation of soot is pre- 
judicial, a smaller amount of north-country coal should be 
used. 

304. Tools and Eubbish of all hinds should he taJcen care- 
fully from the Boilers after Repairs. 
Whenever boilers are opened for any purpose, the 
stokers should not be permitted to take oakum or pieces 



264 DUTIES TO ENGINE ON AEKIVING IN HAEBOR. 

of wood witli them into tlie boiler to sit on ; for these sub 
stances are apt to be let down between the water-spaces or 
tubes, and neglected ; remaining there, they form a nucleus 
for deposit, and will ultimately prevent the water from 
coming in contact with the iron ; moreover, they are apt 
to get to the bottom of the boiler, and, from the vortex 
occasioned by blowing off, to find their way into the pipe, 
and completely choke it up. After a vessel has been under 
repair, the boilers should be examined most carefully, that 
any thing that may have been left in them may be hauled 
out through the mud-hole door: rivet-bags have been 
known to have been left behind. All substances made of 
hemp should be taken out with care ; for calcareous sub- 
stances seem to have a peculiar af&nity for that material. 
Spare rivets, or pieces of loose iron, are to be looked for. 
Stokers have been known to put their dirty engine-room 
clothes in the boiler to give them a good boiling ; this 
should by no means be allowed, for they may get adrift, 
and stop up the pipes. 

805. Imjpure Air in the Boilers. 
When the man-hole doors are taken off with a view to 
sending men in to examine the boilers, the gauge-cocks 
should be opened, and also the safety-valves; for if all 
these should be closed it will be found that the air will be- 
come vitiated, and after a little time candles or lamps will 
burn with difficulty, proving that the air will become unfit 
for respiration. 

306. Screw-gearing in Screw-steamers. 
When screw-steamers are fitted with gearings connect- 
ing the engine with the propeller, the gearing should be 
examined occasionally to discover whether the cogs and 
teeth are defective. If any of the cogs are loose, they may 
be secured in their places with pieces of fine canvas and 
white-lead. The gearing becomes much worn after a time, 
and it will be necessary to trim up the cogs- the pitch- 



TO PRESERVE BOILERS. 265 

Hues should also be looked to, to see whether they agree. 
Care should be taken that the cogs do not bottom on the 
pinions as the shaft-journals wear away: this has been 
found to be the case in some instances. 

307. Luhncating the Gearing in Screw-vessels. 
Tallow is sometimes used to lubricate the gearing, but 
it has the disadvantage of becoming hard ; moreover, it is 
diflicult to clean the parts of the machinery with which it 
comes in contact ; it is better, therefore, to use a mixture 
of soft-soap and black-lead : this will be found to lessen 
the abrasion and noise, and will not be attended with the 
same difficulties as tallow. 

808. Paddles. ' 
Some paddles are fitted with two plates to them, one at 
the back to receive the nip of the arm, and the other the 
nuts, or else the paddles will be weakened by the screwing 
up. The hook-bolts should not have their hooks too long, 
in order that a few turns out of the nut may suffice to let 
the bolt be unhooked, that the boards may be unshipped, 
bolts and all, and be reshipped with the bolts in ; other- 
wise the bolts may be lost overboard in shipping and un- 
shipping, and time certainly will be wasted in performing 
this operation when perhaps every moment is most precious. 
The nuts of the paddle-bolts should be all of one size, that 
the same spanner may fit them all : much confusion and 
loss of time will be avoided by attending to this circum- 
stance. 

809. Preserving Boilers when not in use. 
A boiler when not in use should either be perfectly dry, 
or plenty of water should be kept in it : mere moisture is 
very detrimental to iron, chiefly because the solution of 
copper from the internal steam-pipe, feed-pipe, etc., carried 
down with it to the bottom of the boiler, is not so diluted 
as when it mixes with a boilerful of water. Fires should 



266 DUTIES TO ENGINE ON AERIVING IN HARBOR. 

be lighted at intervals to dry the boilers. Coal-tar, red- 
lead, and tallow, etc., have been tried as coatings to prevent 
oxidation ; but many parts, from being difficult of access, 
wiU escape notice. We would recommend a trial of the 
following, which has proved successful. Mix a quantity 
of soft-soap with some hot fresh water, and pour this into 
the empty boiler ; then open the blow-out cock, and let the 
water run up to the top of the tubes or flues : the solution 
"being carried by these means to every part of the water- 
space, oxidation will be suspended. There should be about 
3 lbs. of soap to every ton of water. Those parts which 
are above the water, such as the steam-chest, uptake, etc., 
should be coated with soft-soap and linseed-oil. For this 
part mix 2 lbs. of soap with every gallon of oil ; and let 
this be put on before the boiler is filled. 

810. Fitting Mud-hoh Doors. 
In many steamers the mud-hole doors are fitted on the 
outside ; but it is a better plan to have them fitted on the 
inside, and the internal pressure will then assist in keeping 
them in their places. The Meteor some years since re- 
turned from Gibraltar with the bolt broken off the mud- 
hole door, and there was nothing but the pressure of the 
steam and water to keep it in its place ; it had leaked at 
starting, and on screwing it up it broke off. Now had it 
been fitted on the outside, the vessel must have been de- 
tained, to say nothing of the risk arising from letting the 
water pour out of the hole into the engine-room. Since 
the publication of the first edition of this work, a sad 
accident occurred on board a screw-steamer at London 
Bridge-: the mud-hole door was fitted on the outside, and 
when getting up the steam, the joint was discovered to be 
leaky, which the engineer endeavored to remedy by screw- 
ing it up ; the bolt broke, and the door being forced of? 
the engineer was driven by the rush of scalding water to 
the opposite side of the stoke-hole, and scalded to death. 



GETTING UP STEAM. 267 

811. Getting up the Steam occasionally when in Karhor. 

The more any person is in the habit of watching the 
working of engines that have been remaining still any con- 
siderable time, the more he will become convinced of the 
necessity of having the steam up at short intervals. The 
steam should be got up every two or three weeks, and the 
engines worked for a short time. There is not so great an 
expenditure of coal in this as would at first sight be sup- 
posed ; considerably less will be used than would be in the 
inefficient working of the engine, leaving out the wear and 
tear arising from the rusty state of the machinery. When 
the engines are thus worked for the sake of keeping them 
in good order, it will, of course, take place in harbor, or 
elsewhere where the ship is upright, and not rolling about ; 
and it will not be necessary to have so much water in the 
boiler as otherwise would be needful, nor will it be impor- 
tant to have so many nor such active fires. One boiler 
will be sufficient for our purpose ; and with a small quan- 
tity of water it will soon boil, and will serve to keep the 
other boilers dry. Let the fires burn slowly by closing 
the dampers, to allow the water to absorb the heat and not 
permit it to pass up the funnel. There will be two advan- 
tages attending this plan ; less fuel will be used, and it will 
make little or no smoke to black the rigging and sails. The 
small coal may be used for this purpose ; and keeping the 
fires thus, the steam will soon be got up well enough to 
give a few round turns to the engine ; and this is enough 
for the purpose. An engine that has stood by two or three 
months without having the steam up, can hardly be said 
to be in an efficient state, and the coal used in working it 
will be paid for tenfold. Moreover, in cold, damp weather, 
the good effect it will have upon the ship will be very great, 
both on the score of health, by driving off all damps, and 
exhausting the noxious vapors from the holds, to say noth- 
ing of the preservation of the ship by drying up the wet 
about the timbers of the bilge. 

What has here been said goes on the supposition that 



268 DUTIES TO ENGINE ON ARRIVING IN HARBOR. 

the vessel is supposed to be in readiness to move in the 
nsual time of lighting the fires, in which case the engines 
must be kept in perfect order ; but if the vessel be sup- 
posed not to be wanted for any considerable time, it is gen- 
erally allowed that the better plan is to have the boilers 
and engines open, to allow the air to keep them dry. 

In the latter case, from ten to twelve hours warning may 
be necessary to enable the engineers to put on the man- 
hole and mud-hole doors, and replace slides (if taken out), 
and to repack them and the glands. 

It is, however, indispensable that the engines should not 
be allowed to remain in the same position for any length 
of time ; if, therefore, permission be not given to get the 
steam up at intervals, means must be adopted to move the 
engines by turning the wheels by hand. 



J^^ 



812. Turning round the Wheels hy hand. 
With a balanced engine this requires but little force — a 
few hands in the wheel at the extremities of the arms are 
sufi&cient ; but with an unbalanced engine, tackles must be 
used, care being taken to raise all the floats out of the 
water that had been previously immersed. 

813. Turning- Gecur. 
Gearing is now fitted to our screw-ships to turn the en- 
gines. A wheel is keyed to the propeller-shaft abaft the 
engines, with an endless screw-gearing in it ; a lever is con- 
nected with this screw, and a motion being given to it, the 
whole mass of machinery is moved, the wheel and screw- 
pinion being so proportioned that sufficient power is 
obtained. 

814. Raising Cylinder-covers hy Tackles. 

This is the usual mode of raising cylinder-covers : As 
a great strain is required to raise them, the blocks must 
be arranged so as to grant the greatest purchase. Before 
the eye-bolts are screwed into the cover, insert pieces of 



TO KAISE CYLINDER-COVERS. 269 

iron under the flange, tliat the bolts, when screwed in, may 
press on it ; and then, on screwing them in, the cover will 
be separated from the flange of the cylinder. ISTo one shonld 
attempt to work under cylinder-covers when suspended in 
this way, or supported in any temporary manner, for fear 
of accidents. They may be supported by two props of 
stout wood resting on the piston and lashed to the piston- 
rod. 

815. To get the Cylinder-cover of an Engine into its place hy 
the help of Steam, supposing it to he lashed to the Gross- 
head; or to raise it by a similar process. 
To do this, .we will suppose that the pistons are in work- 
ing condition within the cylinder, and that the engines 
likewise are in working order, with the exception of the 
cylinder-covers. Let us suppose the engine which has its 
cover raised to be on its top centre. Let both engines be 
blown through, and a vacuum created in the condenser. 
Now one engine being on its centre, the other will be at 
the middle of its stroke. Let the slide of this latter engine 
be moved carefully by hand, to effect a communication- be- 
tween the condenser and the lower part of the cylinder ; 
the atmospheric pressure acting on the top will then force 
the piston of this engine to the bottom of its stroke, and 
the other piston will now be half-way down. Next per- 
form the same process with the other engine, but very 
gradually, for fear of letting it down too quickly ; and the 
cover which was before half-way down will come into the 
required position. The same method may be employed to 
raise the cylinder-covers by the help of the steam. The 
piston of the engine whose cover is to be raised being at 
the bottom of the cylinder, lash the cover to the cross-head, 
and admit steam above the piston of the other engine which 
is at half-stroke. As the joint has to be broken, this must 
of course be done carefully. Then, when the starting en- 
gine is at the bottom centre, introduce steam under the 
piston whose cover is off, and raise it to the point required. 



270 DUTIES TO ENGINE ON AERIVING IN HARBOR. 

If it be necessary to raise botli covers, the second one should 
be lasted when tbe first piston is half- way np, and tben, 
when this piston is at the top, the other will be half-way 
up. The break on the wheels will control the motion, and 
secure them when high enough. Som'e modern engines 
have man-hole doors in the cylinder- covers, which can be 
taken off to effect repairs of the piston. These remarks 
however, apply only to paddle-engines. 

816. To ascertain if the piston of an engine is tight. 
An engineer is apt to suppose, when the engine does not 
perform its functions according to his expectation, that the 
piston is leaky, and thus allows some of the steam to pass 
from one side to the other without executing any work. 
This can be ascertained when the vessel arrives in port, or 
whenever the engine is stopped. Let the lower steam-port 
be opened for steam, and at the same time open the grease- 
cocks in the cylinder-cover. Now it is clear, if the steam 
can pass between the edge of the piston and the cylinder, 
it will come up through the grease-cups, and make itself 
visible in the engine-room. The engine should remain 
stationary a small space of time ; for if the leakage be small, 
it will be some time before the escape of steam can be 
observed. 

317. Piston hose on the Bod. 
If the piston is loose, and it be impossible to stop and 
secure it, the steam should be throttled for that engine, to 
lessen its force on first entering. When tightening the 
piston on the rod, care must be taken, in driving the key 
up, that it is really acted upon ; that is to say, that there is 
what is technically called draught in the key-way; and 
secondly, that it is not driven up so hard as to split the 
piston, as has been done in some instances. Pistons that 
are secured by a nut and screw need no precaution. They 
should be screwed up as tight as possible. 



BLOWING THROUGH. 271 

318. To separate parts of an Engine that have become rusted 

together. 

Heat is the agent to be employed for this purpose, and 
the readiest plan is to make a fire round the part ; but if 
that be not enough, a mould of sand may be made round 
it, and molten metal run into the recess left for that pur- 
pose. Heated pigs of ballast, slabs of iron, etc., may per- 
haps answer the purpose. 

819. Blowing through when the Blow-valve is injured, or in 
case it be not fitted. 
Let the slide be moved so as to open one of the ports ; 
by this process we shall fill the cylinder with steam : then 
let the slide be reversed, so as to fill the cylinder with steam 
on the other side. By so doing, that which was first ad- 
mitted to the cylinder will pass into the condenser. The 
cold water in the condenser will gradually condense it, and 
it will therefore be ineffective at first ; but by continuing 
the process, the water will be more and more heated, until 
at length, from being no longer condensed, the steam will 
act on the water, and drive it out of the condenser. This 
will, of course, be a slow process ; but it can eventually be 
accomplished by this method, and it can be resorted to when 
other plans fail, or if the blow- valves have become injured 
and useless. 

820. Blowing through delayed by very cold weather. 
In very cold weather there is such a vast difference be- 
tween the temperature of the steam and that of the atmos- 
phere within the engine-room, that steam is very rapidly 
condensed in the steam-pipe as it passes from the boiler to 
the cylinder. In the Bee, the time that elapsed before the 
steam could reach the cylinder was on one occasion de- 
layed so long that it was for a time imagined the stop- 
valve of the boiler was closed. The vessel had lain some 
time without having the steam up ; and as the temperature 
was very low, the damp in the steam-pipe had become 
la 



272 DUTIES TO ENGINE ON AKRIVINa IN HARBOR. 

j&ozen hard, forming a layer of ice round tlie inner surface 
of tlie pipe. Now, althougli tlie steam- valve was loaded to 
7 lbs., and steam was at tlie time blowing off freely from 
tbe steam-funnel, yet it was condensed as rapidly as it 
passed over from the boiler. This was ascertained by 
passing the hand along the pipe, when it was discovered 
that there was a clear line of demarcation between the part 
occupied by the steam and that which still continued frozen, 
the one being hot and the other cold ; and it was interest- 
ing to notice how gradually the steam prevailed over 
the ice, till it came to the jacket, when it rushed in vio- 
lently, and the engine started into motion. Probably this 
delay might have been avoided if the pipe had been coated 
with some good non-conductor, such as felt ; for the plan 
has been adopted since that time, and the same thing has 
never happened again. 

321. Attention to he paid to Engines driving the Screw- 
Propeller. 
Crank-bearings. — The crank-bearings of those engines 
which act directly on the screw-shaft (that is to say, with- 
out the intervention of a driving wheel) require great at- 
tention ; for it will be seen that, as the rotary motion is 
given to the screw, the necessary reaction of the water be- 
ing in a line with the keel, and therefore in a line with the 
shaft, great friction is brought on the sides of the brasses 
of the connecting-rods ; for although the cranks are short 
and rigid, still they will spring, and in so doing will nip 
the sides of the brasses, unless the thrust of the screw-shaft 
be received abaft the engines. In some cases it has been 
received abaft the stern-post, that the external water might 
keep it cool. In all screw-boat engines pipes should be 
brought from the sea-injection to every bearing, to let the 
water run on the bearings if necessary ; for if oil will not 
keep the bearing cool, water will, because it boils at a 
lower temperature, and will carry off the heat from the 
bearing in a latent state. Any one who has observed the 



SCEEW-ENGINES. 278 

good effects of water on a hot bearing must have noticed 
its superiority over oil in such cases. The good effects of 
sulphur arise from the same cause; it fuses at a low tem- 
perature, and so, like the water, carries off the heat. 

In small steamers of easy draught of water, and fitted 
with the screw, the three-threaded screw will be found 
more effective in a sea-way, because it takes a greater hold 
of the water, and the engine is sure to have some part of 
one of the blades immersed, and always meets with some 
resistance, instead of flying off, as it is apt to do with a 
two-bladed screw when the vessel is going head to wind, 
or before it ; but the two-threaded screw will be found the 
best in still water, and in large deep vessels, such as our 
line-of-battle ships, because it does not produce so much 
broken water as the other. 

In starting screw-ships, where the draught of water is 
not great, the engine should at first be set in motion with 
but little steam, which should be supplied with greater 
freedom as the vessel gathers way, or otherwise there will 
be a large amount of slip, from the ship not getting in- 
stantaneously any considerable speed. Something similar 
to this may be noticed on the railroads in starting a loco- 
motive engine, where the wheels slip, or shid, as it is 
termed, upon the rails on the first entrance of the steam. 

Screw-ships ought to have a water-tight bulkhead fitted 
to the fore-side of the stern-post ; so that if they should be- 
come leaky, the water would not come into the bilge. A 
hand-pump should be fitted, to pump this out in harbor. 
A pipe, with a cock in it, should also be fitted near the 
bottom, and the other end be passed into the condenser, 
that the water may be taken out for the use of the engine 
while under steam without the labor of pumping. 

While in harbor, the cylinders of screw- vessels which 
lie horizontally ought to be kept particularly dry, other 
wise water will remain in the lower parts of the concave 
surface, and in a short time rust and injure the cylinder, 
and will thus render it oval instead of circular, because 



274 PUTIES TO ENGINE OX AEEIVIXG IN HAEBOR. 

the weiglit of tlie piston is on the lower part; therefore, 
when the engine has done its work, plenty of tallow shonld 
be put into the cylinder and slides, to protect them against 
the action of the water. 

The screw-propeller should be disconnected from the 
shaft occasionally, to prevent it setting fast, which is found 
to be the case if it be allowed to remain for any consider- 
able time. The gear by which this is effected should also 
be looked to, to see if dependence can be placed upon it 
when the screw is up. 



CHAPTER IX. 



MISCELLANEOUS. 



822. Methods of measuring the Efficiency of Steam-engines. 
The efficiency of an engine is evidently measured by the 
amount of useful work it can accomplish in a given time. 
Now the useful work of an engine is the product of the 
resistance it can overcome multiplied into the space 
through which that resistance is moved in a unit of time. 
Hence if P represent the number of pounds a steam-engine 
overcomes, and v the number of feet through which that 
resistance is moved in one minute, P x t; is the useful 
work OT power of the engine. But it is found that this pro- 
duct for any tolerably-sized engine requires a great num- 
ber of figures to express it ; and it is on that account not 
only cumbrous, but beyond the powers of the mind to 
realize at the first glance ; on which account it was thought 
advisable by Watt to divide the product so obtained by 
some large number, and so to obtain the result in fewer 
figures more readily appreciable. The first engines made 
by Watt and others superseded the use of horses in pump- 
ing water out of mines ; for which reason it was proposed 
to compare the work of an engine with that which it was 
supposed a horse would do. This quantity, i.e., the pro- 
duct of the weight a horse would raise in lbs. multiplied 
into the height in feet through which he would raise it in 
a minute, was considered to be 88000 ; and therefore since 
tEe time of Watt the measure of an engine's efficiency has 

has always hitherto been oo^on ^ ^^^ ^^^^ is called the 

horse-power of the engine. 

Mr. Atherton, chief engineer of Woolwich dockyard, in 

275 



276 MISCELLANEOUS. 

a recent work on tlie capability of steam- vessels, remarks 
that the foregoing measure has, in marine engineering, be- 
eome practically superseded, inasmuch as the term horse- 
power, as now applied in marine-engine contracts and prac- 
tice, does not specially determine or limit the gross working 
power of the engines ; indeed, it is a well-known and ex- 
pected fact, that the actual power of an engine is frequently 
8 or 4 times that which the nominal power would give. 
He, therefore, to obviate in some measure this defect, pro- 
poses to get a new constant, instead of the number 33000, 
by getting the mean gross effect of several of our best 
marine engines, and dividing this by the mean of their 
nominal horse-powers. The quotient thus obtained, after 
deducting 15 per cent., gives 132000, which number he 
uses instead of 33000. 

323. Duty of an Engine, 
The duty of an engine is a term used to express the effect 
produced by a given quantity of fuel. One chief distinc- 
tion between the power of an engine and its duty lies in 
the fact, that power has reference to time, but duty has not. 
The duty of an engine would be the same whether the en- 
gine were to work for an hour, a day, or a month, whereas 
the power developed would vary as the time. In estimat- 
ing the duty of land-engines, the measure usually taken is 
the result obtained by dividing the effective horse-power 
by the consumption of fuel in the same time, which gives 
the power developed by a unit of fuel. This is expressed 

effective horse-power , _ . . < , 

bv ' ir-^ — r ; whereas tor marine engines the 

'^ consumption of fuel ° - 

inverse of this is usually adopted, the duty being measured 

consumption of fuel ^ • i •, • n -i 

bv -7:r. — ^-^ • 111 either case it is useful, as 

'^ enective horse-power 

affording a comparison of the economy of engines and 

boilers of different construction, irrespective of their size, 

and is more immediately a test of the merit of the boiler 

than of the engine. 



HOESE-POWER. 277 

324. To ohtain the Horse-]power of an Engine. 

1. If an indicator can be used, tlie readiest plan in an 
engine actually at work is to get by means of the indicator 
the pressure on the surface of the piston : from this a de- . 
duction must be made on account of the pressure of the 
uncondensed steam and the friction of the engine ; the result 
will give the effective pressure. (Se6 Indicator and Dy- 
namometer, p. 38, second edition.) 

Again : the space passed over by the piston in one minute 
may be easily got, by multiplying the number of revolu- 
tions of the engine by twice the length of the stroke. 

Let now P' be the effective pressure on the piston, 
v' its velocity : 
Then the effect produced by the steam = P' v' (neglecting 
friction and useless resistances). 

But by the principles of mechanics, P' v' = P v. 

Hence the horse-power of the engine =^k7J7^7^- 

325. On Mercantile or nominal Sorse-power. 

The method proposed in the last article is evidently only 
applicable after the engine has been made and commenced 
its functions. But it is necessary to have some definite 
rule for gaining an idea of the power of an engine to be 
constructed, otherwise contracts could not be entered into 
between the manufacturer and the party for whom the en- 
gine is to be made. And therefore, in sending in tenders 
for engines for Her Majesty's ships, the calculation of the 
power is made by allowing the effective pressure on each 
square inch of the piston to be 7 lbs., and the speed of the 
piston for engines fitted with paddles is as follows : 

For 3 ft. in. stroke, 30 revolutions per min. = 180 ft. per min. 



3 


6 


11 


27 , 


<( 


« 


189 


ii 


4 





it 


2^ 


a 


<( 


196 


it 


4 


6 


(I 


22f 


ti 


« 


204 


*t 


5 





(( 


21 


« 


« 


210 


it 


5 


6 


i< 


19r^ 


a 


(( 


216 


u 



^v- 



278 . MISCELLANEOUS. 

For 6 ft. in. stroke, 18|^ revolutions per min.=222 ft. per min. 



6 


6 


7 





7 


6 


8 





8 


6 


9 






15|i 
15 

131 



226 
231 
236 

240 
244 

247 



And hence ttie following rule adopted by tlie Admiralty 
for horse-power : 

7 X -7854 X c?^ X feet per minute 

33000 

cP X feet per minute . ^ . 

or mm ~~" ^^ nommal horse-power. 

It is, however, expected that the engines, when tried and 
tested by the indicator, will exhibit a considerably higher 
result than that obtained by this formula. 

326. To find the Horse-power from the Evaporation of the 
Boiler. 
. The following rules, adapted to logarithmic computation, 
are formed from valuable investigations by Comte de Pam- 
bour, the substance of which is given below. They are, 
however, attended with great difficulties in practical appli- 
cation, from the fact that the effective evaporation of en- 
gines is not known. If we knew how much pure steam a 
given boiler is capable of evaporating in a given time, 
these formulae would give us every thing that we could 
desire ; but unfortunately this is still a desideratum ; and 
even if the supply of water to boilers of various capabili- 
ties were ascertained with the view of getting the desired 
result, still we must remember that the steam generally 
used in engines is surcharged with watery vapor, and there- 
fore not altogether effective in producing elastic pressure. 
And the state of the steam will vary^from time to time in 
the same engine according to the resistance the engine meets 
with : for it is pretty evident the purer and more elastic 



HOUSE-POWER. 279 

tiie steam, tlie better tlie effect. The table of relative vol- 
umes and pressures (Table A, Appendix) will not there- 
fore apply. (See also Indicator omd Dynamom,eter, 2d ed. p. 
43.) But since the investigations and rules which follow 
proceed on the hypothesis of the applicability of that table 
to the practical working of engines, the theoretical evapo- 
ration deduced from it must be used in the computations that 
follow. The investigations connected with this subject are 
given below, and although independently made, are based 
on those of Comte de Pambour.* But those which are 
given when not working expansively will scarcely ever be 
of any practical use, since that condition is never fulfilled ; 

* The steam in the steam-chest of a boiler is in a difiFerent state 
from what it would be if it were shut up in a vessel apart from the 
water which generated it ; for in the latter case it might be heated 
and cooled again, and its elasticity might be increased by diminish- 
ing the volume, and afterwards expanded, and it would obey the 
same laws as other elastic fluids ; but such is not the case when in 
contact with the water from which it was formed, for then additional 
particles are continually being added to the original steam, or re- 
turning from it into the fluid state. Experiments have been made 
at various times for the purpose of establishing some law connect- 
ing the pressure of the steam with its density, but not with any sat- 
isfactory result. Empirical formulae have been proposed by Dulong, 
Arago, Southern, Tredgold, and others, giving a relation between 
the pressure and temperature ; but these are too complicated to be 
made available for practical purposes. After stating these, and 
showing the way in which they ought to have been turned to ac- 
count, M. de Pambour gives one of his own, which, he says, suffi- 
ciently accords with facts to be practically useful, and has the ad- 
vantage of being tolerably simple when introduced into investiga- 
tions. 

Let S = the quantity of water evaporated each minute ; 

Y=:the quantity of steam formed from it under the pressure 

p (in lbs. per square foot). 
y 
Then — is called the relative volume of the steam under the pres- 

sure p. 

and 



1 



h a-^hp 
where a -= -00004227 
and h = -000000258 



280 MISCELLANEOUS. 

as in all engines the steam is cnt off before tlie end of the 
stroke by the slide, altbongh the expansive gear be not 
■used. Practical rules deduced from these investigations 
will now follow. 

Again, if A be the area of the piston in feet, and n = the number 
of strokes in a minute, I the length of a stroke in feet, c the clear- 
ance of the cylinder in feet, and v the velocity of the piston in feet 
per minute, the space A {l-{- c) is filled with steam at each stroke ; 
and therefore, in ?i strokes the volume of steam = 7i A(Z-l-c). But 

V 

n = —,; and since the volume of steam 

Hence L--_M±A 
Hence g - g^ 

V 1 

But 



S a+bp 
vA{l+c) ^ 1 

SI a-\-bp '•'''{') 

Nowp, the pressure of steam in the cylinder, is, in the case of uni- 
form motion, the same as the resistance to motion on the opposite 
side of the piston ; and this resistance is composed of several parts, 
viz. : 

1. The useful load = R (suppose). 

2. The pressure of the uncondensed steam =pi (suppose). 

3. The friction of the unloaded engine =/ (suppose). 

4. The additional friction for every imit of load, which varies with 
the load, and therefore we may call it <r x R, where <r is some con- 
stant quantity. 

Hence |)=R4-pi+/+<^ X R = (l+<^)R4-l)i+/ 

SZ 
also since a + 6 p = —777-7-^ (from I.) 

SI 



SI 



and &(l + cr)R+a+&pi+/ 



Av{l-{- c) 
SI 



consequently 6(1 + cr)R = . ., , . — {ct+bpi +/) 
which gives the useful load, R, on a square foot. 



EFFICIENCY OF ENGINES. 281 



EULE I. 

Knomng the Evaporation of an Engine, the Speed, and Area 
of the Piston, to find the Horse-power. 

Case I. When not working expansively. — To the logarithm 
of the evaporation (in cubic feet per minute) add the con- 
stant logarithm of 6*510286 ; take the natural number of 
the result, and call it A. Again, to constant logarithm 
2*747750 add the logarithm of the velocity of piston (in 
feet per minute), and twice logarithm of diameter of piston 
(in feet) ; take natural number of the result, and call it B. 
Take B from A, which gives the useful effect. Divide the 
result by 33000, and the quotient will be the horse-power. 

^"■^ • • • ^ ^ " =6lT+7) i i +-C ~A " (« +^?r+7) } 

But A R V is evidently the useful effect of the engine when not 
working expansively, and only requires to be put in a practical form 
by substituting numbers for the constant quantities, and reducing 
the result to a rule. 

Now, according to Comte de Pambour, it has been found by 
experiment that 5 = "14 for well-constructed engines in good work- 
ing order ; alsopi may be taken at 2 ibs. per square inch ; and/at 2*5 ; 

hence pi +/= 4*5 X 144 ; also we will suppose c = — - . • . -, — = ITT 5 
eubstituting these values, we get the useful effect 

.3 ,,; I ?? S — -7854 d^ V (-00004227 -f -000000258 X 
08 X 1*14 (21 ^ 



•000000258 X 
144 X 4-5) I 

20 

Now — -=[6-5102861, the square bracket being 

•000000258x1-14x21 i- J' i 5 

used to designate a logarithm. 

And -7854 x (-00004227 -f -000000258 X 144 X 4-5) = [2-747750] 

^, , [6-510286] S— [2-7477501(^2^ 

the horse-power =^ -^^^ . . (A) 

from which we have Rule I., Case I., given above. 

If, however, the engine work expansively, let I' be the space per- 
formed by the piston before the expansion commences ; and let p be 
the pressure of steam before expansion, and p' the pressure at any 



282 MISCELLANEOUS. 

Case II. When the Engine is working expansively. — To 
tlie logaritlim of the evaporation add tlie constant logaritlim 
6*5 3 1475, and to this add logarithm in column 8, Table E 
(Appendix), corresponding to the degree of expansion as 
expressed in the left-hand column ; take the natural niim- 
ber of the result, and call it A. Then proceed to find B, 
as before, and divide by 33000. 

Example I. — The boilers of a pair of marine engines 
evaporate 284 cubic feet an hour for each engine; the 
diameter of the piston is 80 inches, and the velocity 220 
feet a minute ; find the horse-power. 

instant of the motion afterwards, the piston at that instant being 
supposed to have described the space x. Now, if s be the quantity 
of water that formed the steam with which the cylinder is filled, 

A(r+c) 1 



and 



A_(ac+_c)__2_ 



x-\-c a-{-hp 

V + c 

Hence the pressure on the piston being p' A, we have 

And the work done while traversing the small space d x (suppos- 
ing the pressure invariable for this infinitesimal space) =^p'.A.dx 

= V6- + l>;A(r+c)^-:j^— ^Acio; 
and the work done by expansion 

=(|+p)A(r + c)/^^-fA/<i» 
(the integral being Umited by the values a; = Z' and x — I) 

= (! + !)) A(Z'+c)log.fa;+c-^Aa;+Cor. 



{x = V) =- + pAr-hclog.£r+c-^Ar + Cor. 



EFFICIENCY OF ENGINES. 



283 



284: 

Here S = -ttft = 4*733 cubic feet a minute. 
60 



d= 



80 



Then log. S. 
Constant log. 



12 

t; = 200 

•675136 
: 6-510286 



6MQ feet. 



log. 15326000 = 7-185422 



A = 15326000 
B= 5469000 



9857000 
33000 



Constant log. = 2*747750 
log. 220 = 2-342423 

log. 6-666 = -823865 
log. 6-666 = -823865 



log. 5469000 = 6-737903 



= 299 nearly. 



(x = Z) =(| + i>)A(Z' + c)log.a(Z + c)-| Al+Cov. 

And if we add to this the amount of work done before expansion, 
we shall get the whole work during one stroke of the engine. 

But the work done before expansion commences = p A Z' . • . the 
whole work done during one stroke 

l + c . I' 



For the sake of conciseness write C for log. s , 

t -re t -T c 

Then the work done in one stroke 

= (^+p)A(Z' + c)C-|Ai 
Again, since the mean resistance to the motion is the same as in 
the former case, viz. ( 1 + 6 R -f p i +/ ) A, 

.-. (lHhsR+Px+/)AZ-(^+p)A(Z'-fc)C-|Ai 



284 MISCELLANEOUS. 

It is evident that engines will do more work at some 
velocities than they will at others ; for, to take extreme 
caseS; we may so increase the load that the speed of the 
engine becomes reduced till it can scarcely, if at all, turn 
its centres, in which case the product of the load moved, 
multiplied into the velocity, is very small ; and again, if 
we go to the other extreme, we may increase the speed of 
the engine by diminishing the load, till the engine can do 
little more than overcome its own resistance, in which case 
the useful effect is scarcely any thing ; there is therefore 
some intermediate speed at which the engine will move to 
enable it to produce the greatest useful effect. Now De 

Now, to avoid the use of the quantity p, we must call to mind 
that the space A ( Z' + c ) is filled with steam of pressure p at each 
stroke. 

If . • . the evaporation be S, and the number of strokes w, we shall 
have 

A(r4-c) 1 

V 

But ^ = 7 if ^ be the velocity in feet per minute. 

V . V-\-c _ 1 

Z* • S ~a-\-hp • (II-) 

(a+&p)A(Z+c) = -^ 

. • . substituting this in the equation, we have 

|R(14-5)+i>i+/}AZ=:4^.C-^AZ 
^ J bv b 

bv o 
AK(l+«)=-|^-(f+p.+/)A 

Hence AEr(l + «)=^- (|+2),4-/) A«; 

and AR« = .ji-^(SC-(^+;,,+/)A«) 






±_^|(SC-(a+6^.+/)A»J 



■PT^FICTENCY OF ENGINES. 285 

Pambour shows that this will be accomplished by making 
the engine go as slow as it can to consume all the steam the 
boiler generates, in which case the pressure of the steam 
in the cylinder approaches to that in the boiler. It is 
manifest that they can never be practically equal ; but the 
more nearly we arrive at this point the better. If the en- 
gine were to go slower than this, there would be a loss of 
steam at the safety-valve. The engineer, on this account, 
likes to see the steam just making itself visible at the 
safety-valve, well knowing that he gets then the most he 
can expect from it. In the marine engine the resistance 
and velocity of a given engine are always connected to- 
gether, from the circumstance that the resistance of a given 
surface varies as the square of the velocity ; so that the 
only way of reducing the speed is by increasing the resist- 



V l-\- c 

and the log. of or -rj- f- log. f — - — corresponding to the given 

t 4" c L -f- c 

degree of expansion yis given in column 3, Table E (Appendix). 

TT TTT. [6-531475] S. 0- [2 -747750] (^^t; .^. 

Hence H.P.^i ^—^ ^ . . . (B) 

from which we deduce Rule I, Case II. p. 282. 



To determine the Velocity of maximum useful effect. 

It has been said above, that when the velocity of the engine is 
such as to give the maximum effect, the pressure of the steam in 
'the cylinder approximates to that in the boiler. But if p be the 
pressure in the cylinder, we know by equation (I.) that 
A.v{l-{-c) 1 



SZ a+fcp 



when the engine is, not working 



vA(Z'+c) 1 

expansively ; and that by (II.) ^-^ = — when working 

V 
at the grade of expansion represented by j . Hence if we consider 

p to represent the pressure of the steam in the hoiler, these ex- 
pressions will give us the velocity corresponding to the maximum 
useful effect. 



236 MISCELLANEOUS. 

ing surface of the floats ; and the engine may be considered 
to be at its best speed when the floats are of such a size 
that the steam in the boiler is on the point of blowing off. 
De Pambour's investigation, founded on this fundamental 
principle, is given below ; the practical rule depending on 
it is as follows: 



EULE II. 

To find the Velocity of an Engine corresponding to the maxi- 
mum useful eJl 



Case I. — When not working expansively. — To logarithm 
of pressure (per square inch) in the boiler add the con- 

g 7 I 

Equation (I.) gives v=^— (C) 

A.-l-\- ca-\-hp 

and (11.) ^;=^L^_J__ .(D) 

A.{l-\- c) a-\-h p ^-' 

g ; I 

Taking equation (C), v= — . — — _ 



A'Z+ C a-\-bp 

S I 100000 



AZ-Lc (4-227+ [0-569982] p) 

SI 100000 



d2X-7854x (Z + c) (4-227+ [0'569982]p) 

also ^„,f „ , , X 100000= [5-083720] 

•7854x(Z+c) ^ ' 

„ S [5-083720] 

H pnpp 0} = = = 

d^ (4-227+ [0-569982] .p) 

From which formula we get Bule II. Case I., given above. 

SI 1 

Again, taking equation (^\'^=j^ir^^ . ^qp^ 

100000 

SI -7854 



"">.(?'+ c) (4-227+ [0-569982]p) 

_ SI [5-104909] 

~ c^^(^' + c) (4-227 + [0-5699^2] p) 

Now^he log. of Tj-. — to the given degree of expansion y is given 
I +c * 

in column 2, Table E (Appendix). 



EFFICIENCY OF ENGINES. 287 

stant logaritlim 0*569982; take out the natural number 
corresponding, and add to it the number 4-227. To the 
log. of this sum add twice the logarithm of the diameter of 
the piston in feet. Call the result log. A. 

Again, to logarithm of evaporation (in cubic feet per 
minute) add constant logarithm 5*083720, and from this sum 
subtract log. A : the result will be the logarithm of the 
velocity of maximum useful effect. 

Case II. When working expansively. — First find log. 
A, as before ; then to log. evaporation in cubic feet per 
minute add constant log. 5*104909, and the number from 
Table E (Appendix), col. 2 corresponding to the amount of 
expansion as tabulated in the column on the left hand, and 
from their sum subtract log. A, and the result will be the 

Hence we get Rule II. Case II., given above. 
Again, since by equation (A) 

HP— [^'^IQ^Se] S — [2-747750] dl?v 
■ '~ 33000 

33000xH.P. = [6-510286] S— [2-747750] (fv 
or [6-510286] S = 33000 XH.P.+ [2-747750] d?v 

_ [2-747750] drv-{- 33000+H.P. 
"~ [6-510286] 

Hence we get Rule III. Case I., given in p. 289. 
Similarly, from equation (D) we get 

1 /s-io^^^^^-i-s . 

' ^ 4-2271 



^ [0-569982] V d'v 

whence Rule IV. Case II. p. 291. 

Again, to find the diameter of the cylinder. 
Since, from equation (A), 

IT p — [6-510286] S— [2-747750] d'v 
■ '~ 33000 

.-. [2-747750] c«-v= [6-510286] S — 33000 H. P. 
[6-51028 6] S — 33000 H. P. 
~ r2-747750]T^ 

. ( [6-510286] 8 — 33000H . P. \ 
^= IX V [2-747750] I' '"' / 

which gives Rule V. Case I. p. 292. 
19 



288 MISCELLANEOUS. 

log. of the velocity corresponding to the maximum useful 
effect. 

Example 2. — Find the velocity of maximum useful 
effect of the engine mentioned in Example 1 ; the pres- 
sure of the steam being 10 lbs. above that of the atmos- 
phere. 

Here ^ = 25 lbs. 

log. i? = 1-397940 log. S = -675136 

constantlog.= 0-569982 constantlog.= 5-083720 



log. 92-88 =1-967922 ^ 5-758856 

4-227 log. A = 3-634198 



log. 97-107 = 1-987250 log. 133 =2-124658 

log.diam. = -823865 
= -823865 



log. A =3-634198 

.*. velocity of maximum useful effect = 133 feet. 

Also, if the engine be working expansively, we have from equation 

(B) 

[6-531475] S. C — [2-747750] d'v 
' 33000 

33000 X H. P. = [6-531475] S C — [2-747750] (fv 

[2-747750] (ft; = [6*531475] SO — 33000 x H. P. 

^, [6-531475] SO — 33000 X H. P. 

^^^ ^= [2-747750]..; 

[6-53 1475] S C — 33000xH.R 
[2-747750] . V 

from whence we deduce Rule Y. Case II., given in p. 292, 
Again, from equation (I.), 

Av(Z+C)_ 1 



=>/(' 






I- 1 



}0l 

p, and is given in Table A (Appendix). 



But — r— — is the relative volume of the steam under the pressure 

a-\- bp ^ 



EFFICIENCY OF ENGINES. 289 



EULE III. 



To find the effective evaporation of a condensing Engine of 
given dimensions and horse-power, the Piston moving vnth 
a given velocity. 

Case I. Where the Engine does not worh expansively. — 
To tlie constant logarithm 2*747750 add twice the logarithm 
of the diameter in feet, and logarithm of velocity of piston 
in feet ; take the natural number of the result, and add to it 
the useful effect (or the horse-power of the engine x 33000). 
From the logarithm of the sum subtract the constant loga- 
rithm 6'510286; the result will be the evaporation in 
cubic feet per minute. 



Let this: 


= r 




Av(Z4-c) 


-X 


•7854 X d'v 


l.r 




r 


d'v 







[0-83720] r 

■whence we obtain Kule VI. Case I., given in p. 295. 
Again, from equation (B), 

_ [6-531475] S . C — [2-747750] dry 
' '~ 33000 

. • . [6-531475] S . C = [2-747750] d'v -f 33000 X H. P. 
[2-747750[d''^-f33000 X H.P. 
^^ [6-531475]. C 

from which we get Rule III. Case II. p. 290. 
Again, by equation (C), 

_^_Z_ _1 

AZ+c a-\-bp 
which was subsequently reduced to 

S [5-083720] 



d' (4-227+ [0-569982] p) 
whence 4-227 + [0-569982] p = ^ ^^'^^^^l 

and [0.569982]p^^-i^^?a_4.227' 



290 MISCELLANEOUS. 

Case II. When working expansively. — To the constant 
logarithm 6*531475 add the logarithm of the number cor- 
responding to the degree of expansion, as given in col. 3, 
Table E (Appendix), and nse this logarithm instead of the 
logarithm 6*510286 in the preceding case. The result will 
be, as before, the logarithm of the evaporation in cubic feet 
per minute. 

Example. — Given the diametei*of the piston of an engine 
of 200 H.P. 60 inches, velocity of piston 210 feet ; find the 
effective evaporation when not working expansively. 
Here diameter = 60 inches = 5 feet 

horse-power = 200 . * . useful effect = 6600000 
velocity of piston = 210 feet. 
Then, by Case I. 

constant log. = 2*747750 
log. diameter = /698970 

^ [0-569982] I d'v ) 

from which we get Rule lY. Case I. p. 291. 

Again, if the engine work expansively, the space V •\- c is filled 
with steam at each stroke, and the formula becomes 

Xv[l'-\-c) _ Jl 

A.v{l'-\-c) 



S 



a-\-hp 
_ Xv{l'^c) 
~ l.r 

_ -7854^21;. (r + c) 
~ T7r 

■ _ d''v.{V^c) 
~ [0-104909] Z.r 

[ 0-104909 ],-j—^ 
•- Z+c 

Now 7— — is given in column 2,-*^Table E (Appendix) ; and r is 
I -\- c 

to be obtained, as before, in Table A. Hence we get Eule YI. Caso 

11. p. 296. 



EFFICIENCY OF ENGINES. 291 

log. diameter = '698970 
log. velocity = 2-322219 



log. 2937000 = 6467909 
usual eftect = 6600000 



log. 9537000 = 6-979412 
constant looj. = 6*510286 



log. 2-945 = -469126 
, • . the effective evaporation = 2*945 cubic feet. 

RULE lY. 

To find the Pressure of Steam in the Cylinder, knowing the 
effective evaporation. 

Case I. Not working expansively. — To logarithm of - 
the evaporation add the constant logarithm 5*083720 ; call 
the result log. A. 

Also to twice logarithm of the diameter in feed add 
logarithm velocity of piston, and subtract their sum from 
log.'A.- 

Find the natural number of the resulting log., from 
which subtract the number 4*227. 

From the logarithm of the difference subtract the constant 
logarithm 0*569982, and find the natural number of the re- 
sult, which will be the pressure of steam in the cylinder 
per square inch. 

Case II. When working expansively, we have the following 
modification of Case I. — To log. of evaporation add the con- 
stant log. 5-104909, and the number in cokimn 2, Table E 
(Appendix), corresponding to the proper degree of expan- 
sion, the result will be log. A ; then proceed as before. 

Example. — Find the pj^essare of steam in the cylinder 
of the engine investigated in the last problem. 



MISCELLAXEOUS. 

log. evaporation = -469126 
constant log. = 5-083720 



log. A 


= 5-552846 


log. diameter 
log. velocity 


= -698970 
= -698970 
= 2-322219 




3-720159 


log. 68-02 
4-227 

log. 63-793 
constant log. 


= 1-832687 

= 1.804753 
= -569982 



log. 17-17 =1-234771 
.*. pressure = 17*17 lbs. per square inch. 

KULE Y. 

To find the Diameter of a Cylinder to work at a certain speed, 
knowing the evaporating 'power of the Boiler, 

Case I. When not working expansively, — To logarithm of 
the evaporation add the constant logarithm 6-510286. 
Take the natural number of the resulting logarithm, from 
which subtract the useful effect, or H.P x 33000. Find 
the logarithm of the difference, which call log. A. 

Again, to logarithm of velocity of piston in feet add the 
constant logarithm 2-747750. Call the sum log. B. 

From log. A subtract log. B, and divide by 2 ; the result 
will be the logarithm of the diameter in feet. 

Case TI. When working expansively, we have the following 
modification of the preceding case. — To logarithm of the 
evaporation in feet add the constant logarithm 6-531475, 
and the number taken from column 3, Table E (Appendix), 
corresponding to the proper degree of expansion. Take 



EFFICIENCY OF ENGINES. 293 

the natural number of the resulting logarithm, from which 
subtract usefal effect (or H.P. x 38000) ; find the logarithm 
of the difference, which call log. A ; then proceed as before. 
Example. — What must be the diameter of the cylinder 
of a 100 H.P. engine, connected with a boiler evaporating 
1*5 cubic feet a minute, the speed of the piston being 180 
feet? 

log. 1-5 = -176091 

constant log. =6-510286 



log. 4857000 = 6-686377 
3300000 = useful effect 



Again, 



log. 1557000 = 6-192289 = log. A. 



log. B. 



log. 
cons 


180 
jtant log. 

3-932 


= 2-255272 
= 2-747750 




5-003022 




6-192289 
5^003022 




2)1-189267 


log. 


= -594633 



. • . the diameter = 3*932 feet, or 47-184 inches. 

As an example on expansive working, let us proceed to 
find the diameter, that the engine may have the same 
power, and evaporate t% of a cubic foot per minute, the 
steam being cut off' at J the stroke. 

Here log. 0-9 =1-954242 

constant log. = 6-531475 
from Table E.= -191730 



log. 4758254 =6-677447 
3300000 = useful effect 



294 MISCELLANEOUS. 

log. 1458254 = 6-163757 = log. A. 
as before 5-003022 = log. B. 

2)1-160735 

log. 3-805 = -580368 
. • . tlie diameter = 3-805 feet = 45*660 inclies. 

Tofirid the pressure of the Steam in the Cylinder in the two 
cases just investigated. 
Case I. log. 1-5 = 0-176091 

constant log. = 5-083720 



log. A = 5-259811 

log. d = 0-594633 

= 0-594633 

log. velocity = 2-255272 

3-444538 



log. 65-351 = 1-815273 
4-227 



log. 61-124 = 1-786211 
constant lo":. = 0*569982 



log. 16.45 = 1-216229 
.* . pressure of steam = 16.45 lbs. 

Case II. log. 0-9 = 1-954242 

constant log. = 5-104909 
from Table E = 0-259594 



loff.A. =5-318745 



o 



log. d = 0-580368 

= 0-580368 

log. velocity = 2-255272 

3-416008 
log. A. = 5-318745 



EFFICIENCY OF EN"GINES. 295 

log. 79-993= 1-902737 

4-227 



log. 75-766= 1-879531 
constant lo^. = 0-569982 



log. 20-39 = 1-30954:9 
.'.pressure = 20'39 

These two cases are remarkable for their results, and 
deserve especial consideration. The two engines have the 
same power, they have also the same speed, and, therefore, 
as far as effects are concerned, they are identically the 
same ; but the evaporation of the one is 1-5 cubic feet a 
minute, and that of the other -9, or, in other words, we 
may say the consumption of fuel in the two engines is 
as 15 to 9. Kow this arises from the fact that the one 
engine uses the steam at uniform pressure throughout the 
stroke (viz. 16-45 lbs.), and the other, commencing with 
steam of 20-37 lbs., works expansively. It is also to be 
noticed that any advantage arising from the difference in 
the areas of the cylinders is in favor of the one of greater 
consumption. 

EULE YI. 

To find the Evaporation of Water in the Boiler of an Engine, 
knowing the velocity and diameter of the Piston^ together 
with the Pressure of Steam in the Cylinder . 

Case I. When not working expansively. — To twice the 
logarithr^ of the diameter in feet, add the logarithm of 
the velocity in feet ; call the result log. A. Again, to log. 
of the relative volume of .steam in Table A (Appendix), 
corresponding to the pressure of steam in the cylinder, add 
the constant log. -083720, and call the result log. B. Take 
log. B from log. A, and find the natural number of the dif- 
ference, which will be the evaporation of the boiler. 



296 



MISCELLANEOUS. 



Case II. When working expansively. — Find log. A as be- 
fore ; then to log. of relative volume corresponding to tlie 
pressure of steam in tlie boiler, as given in Table A (Ap- 
pendix), add the logarithm of number given in column 1, 
Table E (Appendix), corresponding to the given degree of 
expansion, and to this add the constant logarithm '104:909 ; 
call the sum log. B ; take this from log. A, and find the 
natural number of the result for the evaporation. 

Example 1. — The diameter of the Bee's cylinder is 20 
inches ; the number of revolutions when working with the 
highest grade of expansion (J of the stroke) is 30, the length 
of stroke 2 feet ; find the effective evaporation : the pres- 
sure of steam in the cylinder is 10 lbs. above the atmosphere. 

Here, relative volume corresponding to pressure 25 lbs. 
= 1044; and log. 1044 = 3-018700. 

Again, log. from tables for |(= \) = -602060. 

Hence log. df = -221675 

= -221675 
z.v =2-079181 



Again, 



log. A 

log. 1044 
from table 
constant log. 

log.B 
log.S 



= 2-522531 



= 3-018700 
= -602060 
= -104909 



= 3-725669 



= 2-796862 



.•.S = -0627. 
Example 2. — Find the horse-power of the Bee's engine, 
at the foregoing degree of expansion, 
log. S = 2~796862 constant log. = 2-747750 

constant log. = 6-531475 log. velocity = 2*079181 

from tables = -349277 log. diameter = -221675 

t( _-. '221675 

log. 476500 = 5-677614 ' 

186300 = 5-270281 



EFFICIENCY OF ENGINES. 



297 



A = 476500 
B = 186300 



useful effect = 290200 
H.P. =8-8 

Example 8. — To find tlie effective evaporation in tlie 
boiler of the foregoing engine, the steam being cut off by 
the slide, and the horse-power the same as that in the 
result of the last question. 

Note. — The slide of the Bee cuts off the steam at two- 
thirds of the stroke. 

Now, by Kule III. Case II. 
constant log. = 6-531475 



log. from tables = -120903 
6-652878 



const, log. = 
log. diam. =: 

log. velocity = 



2-747750 
•221675 
-221675 

2-079181 



log. 186300= 5-270281 
290200= useful effect 



log. 476500 = 
constant log. =: 



5-678068 
6-652878 



log. -1061 = 1-025685 

Example 4. — The steam being cut off by the slide as in 
the last example, and the horse-power and cylinder as be- 
fore, to find the pressure of steam in the cylinder. 



log. S = 1-025685 

constant log. = 5-104909 
log. from tables = -148911 

4-279505 
2-52253 



log. velocity =2*079181 

log. diameter = -221675 

= -221675 

2-522531 



log. 57-14 = 1-756974 

4-23 
log. 52-91 = 1-723538 
const, lo^. = -569982 



log. 14-24 = 1-153556 



• . the pressure of steam is 14-24 lbs* 



298 



MISCELLANEOUS. 



These examples, when analyzed, will be found very prof- 
itable. Examples 1 and 2 correspond to the expansive 
working of the engine, and Examples 3 and 4 to the 
throttle-valve ; for in the latter cases the steam must be 
throttled to produce the same revolutions as when work- 
ing expansively. Now the cases are these : 

(1.) By expansive working, the pressure of the steam 
before expansion is 25 lbs. per inch, and the effective evap- 
oration is '0627 cubic feet a minute; and (2) when the 
steam is throttled, the velocity and horse-power are pre- 
cisely the same, but the pressure of steam in the cylinder 
is only 14-24 lbs., and the effective evaporation is '1061 ; 
we obtain therefore an economical result by using steam 
at the higher pressure, and expanding it, over what we 
should get by the throttle-valve under similar circum- 
stances, in the ratio of 627 to 1061 in this particular in- 
stance. 

827. On the Screws of Steam-vessels. 
(Continued from page 145.) 
We have before stated that the surface of a screw may 
be conceived to be produced by supposing a line to travel 

along the line T'Q' at the 
same time that it revolves 
around it. LetT'Q'OPbe 
the surface so generated: 
then this surface is called 
the hlade of a screw; T'Q' 
is called the length; the 
angle P H is called the 
angle; and what T'Q'would 
become if O H were con- 
tinued through a whole revolution, is called i]iQ pitch of the 
screw; and OP is called the thread. Now since the angle 
P H is constant, if the triangle P H were unfolded on 
paper, itwould iormd^plane triangle, of which PH (the length 
of the screw) would form the perpendicular, and H (the 




AEEA OF SCREW-BLADE. 299 

portion of the circumference described) would be^the base, 
and P the hypothenuse. Also, if P'O'H' be another 
cylindrical surface surrounding T'Q', it may similarly be 
formed into a triangle, whose perpendicular P'H' is also 
the length of the screw, but having a smaller base O'H', 
and therefore a larger angle P'O'H' : hence we see that 
screws may have the same pitch but different angles, if 
their diameters differ. 

828. To find approximately the Area of a Screw-hlade 
T'Q'OP. 

If we trace a series of curves such as P'O' on the sur- 
face, we may obtain approximately the area of the surface 
by the following means. 

Let all the lines P . . . . P'O' .... T'Q' be added 
together, and divide the result by the number of lines so 
added to get a mean breadth of the surface. Then, if this 
be multiplied by Q'O (the radius of the blade), it will give 
the area sufiiciently near for all practical purposes. 

The only thing we have, therefore, to do is, to explain 
the method of getting the lengths of P, O'P', etc. To do 
this, let us bear in mind what was before said in explana- 
tion of the principle of the screw. Thus, it was said that 
every portion of P had the same inclination to the base ; 
hence it follows that POH is a right-angled triangle 
wrapped round a cylinder, and it may evidently be un- 
folded on paper. 

Let BAG, therefore, be 
the right-angled triangle, 
having BC = PH or T'Q' 
(the length of the screw) and 
AB = OP; and therefore 
A C = H 0. Now by ex- 
amining OT'H' in the curve 
surface, we see, as was stated, 'that it also will unfold into 
a riglit-angled triangle, having the same perpendicular, but 
a less base, and therefore a grminr aivjle at the base ; and 




?00 



MISCELLANEOUS. 



hence B C will serve also for tlie perpendicular of this tri- 
angle and some length AiC will serve for the base, and 
consequently AjB will serve for the line OT'. Now our 
object in drawing the lines O'P', etc., being merely to get a 
sufficient number of means between P and T'Q', we shall 
effect the same object by dividing A C into any number 
of equal parts, and drawing the straight lines B A, B Aj. 
Generally speaking, two means, as in the figure, or even 
one, will be amply sufficient, and the surface of the blade 
will be 

AB+A.B+A3 + CB .p^, 

4 

Let the outer edge 
of the propeller be ac- 
curately measured 
and laid down upon 
paper according to 
some scale ; and let 
A B represent this 
edge. On A B describe 
a semicircle A C B. 
Measure the length oi 
the propeller; and, on 
the same scale as be- 
fore, let B C be the length drawn from the point B within 
the semicircle. Join A C ; then A C B will represent the 
triangle P H. 

329. To find the Angle of a Helix or Thread of a Screw- 
propeller. 
The angle of a helix is the angle (at the circumference) 
between the outer edge, or thread, and the plane perpen- 
dicular to the axis. Hence it is the angle BAG above. 

Construct, therefore, the same diagram as before, viz., by 
drawing a line A B to represent the outer edge of the pro- 
peller, and after describing on it a semicircle ACB, within 
this semicircle let the line B C be drawn equal in length to 




PITCH OF THE SCREW. 301 

the length of the propeller (as measured along the axis) ; 
then join A C, and the angle B A C at the base is the 
angle of the propeller. This angle may be measured by 
the aid of mathematical instruments, or its value may be 
calculated: thus let AB or P = a, and B C = ?; then sin. 

B A = f whence the angle may be found by logarithmic 

tables. 

830. To find the Pitch of a Screw-propeller. 

Knowing the diameter of the propeller, find the circum- 
ference of a circle of this diameter; and if a right triangle 
be constructed, having the angle at the base equd to the 
angle of the propeller, as found in last article, the perpen- 
dicular will be the pitch required. This is clear from what 
was stated in p. 298. 

2^=tan.BAC 
base 

and pitch = base x tan. BAG. 

= 3-14159 X diameter x tan. BAG. 

Table I. has been calculated from this formula, for pro- 
pellers of 1 foot diameter ; and consequently if the number 
given there be multiplied by the diameter of the propeller, 
the result will give the pitch. 

331. What must be the Pitch of a Screw to advance a given 
number of Knots (a) per hour, when making a given num- 
ber of revolutions {n) per minute. 

Let X = the pitch of the propeller, in feet 

wx = space advanced per minute, ditto 

60 71 ic = space advanced per hour, ditto 

60 nx 

^^^^ = space advanced per hour in knots 

eOnx _ 
6080 """^ 



802 MISCELLANEOUS. 

6080 a__804 a 
60~* n~"~3~" n 



or £c = 



101 - nearly. 



332. Given the speed of a ship and the slip per cent of the 
Screw, and the number of revolutions of the Propeller, to 
find the Pitch of the Screw. 

Let a be the speed of the screw in knots ; 
h be the speed of the ship in knots ; 
m = the slip per cent. 
Then, preserving the same notation as in the last pro- 
blem. 

60 nx 



But 



6080 

a — b m 





a 


100 




00a- 


- 100 5 = 


ma 




(100- 


— m)a — 


100 5 






a = 


100 
100— m 






60ncc 


100 5 






6080 ~ 


100 — m 






.* . a; = 


60800 h 






6n 100- 


-m 



833. To find accurately the Surface of a Screw-blade. 

Let 0' P' * = s ; H Q' = /3; Q T = Z ;• 
P H = a ; Q' H = «. 
. • . H = a. /3 ; P H = a /3 tan. a = 6 /3 (suppose) 
Let P' 0' H' ^ d, and Q' H' = r. 

Hence, since P' H' = 0' H' tan. d 

= r i3 tan. 
P H = H tan. a 

* See diagram p. 298. 



POWER OF THE SCREW. 303 

= a j3 tan. a 



r tan. o =a tan. a = 6 

b 
~ tan. = - 



Now s = 0' P' = 0' H' sec. 



= ri3. \/l + tan.?0 

And the surface 
=fsdr 

= i5f^ r^ + 6^ dr 
= |{6Mog.,(r + v/'F+7) 4-r^7qr6-- 1+Cor. 

^ar = 2|^^^^'A 5 J+a^a+b J 

^ f . 1 / l+>/l + tan.-a >^ •) 

= - |anan.^alog..V ^^^^ )+a see. ,| 

= — |tan.^a . \og.^{ ^.^^ ) + sec. a| 

a^3 , , . * . \ 

= -— -(tan.^ a log.^ cot. 2+ ^®^' **) 

a a /3tan. a^ . . <* , \ 

= -(tan. a log. ^ cot. - + cosec. o) 

or, if expressed in tenns of the length, 

a I a 

= -r-tan. a log.^ cot. ^ -f cosec. a) 

334. Investigation of the Power exerted by a Screw. 
Let n — the number of revolutions per minute of the 
screw. 

. * . 2 rt . 71 = the angle described in a minute. 
And hence the velocity of a particle of the screw M 
about the axis T' Q' is 2 7t . n. r. 

, Now, using the same notation as before, Z P' 0' H' = o, 
therefore the motion of the screw makes the same angle e 
with its surface, at the point M. 

If now this velocity be resolved in direction perpendicu- 
20 



804 MISCELLANEOUS. 

lar to 0' P', the resolved velocity in this direction = 2 .-t n r 
sin. 9. 

Again, if u = velocity of ship in direction Q' T', the 
velocity in direction perpendicular to 0' P' =u cos. d. 
. Hence the difference between these two velocities 
:= 2 Ttnr sin. e — u cos. d. 
But the pressure of the fluid varies as the square of the 
normal velocity ; 

. • . force at distance r oc (2 ft nr sin. 9 — u cos. 9y 
. • . force at distance r —h{27tnr sin. 9 — u cos. ^)' 
where h = pressure on unit of surface moving with velocity 
imity. 

Resolving this force in direction parallel and perpendicu- 
lar to screw-shaft, we have (1) in direction of shaft 

force = k{2 rtnr^m. 9 — u cos. 9^ cos. 9 
and (2) in a plane perpendicular to shaft, 

force — kf^Jtnr sin. 9 — u cos. 9y sin. 9 
and the resolved pressures on the strip sdr in these two 
directions are respectively 

ki2,7tnr^m.9 — u cos. 9f cos. 9sdr 
and k{2 rtnr sin. 9 — u cos. 9j sin. 9 sdr 

•Let now P = pressure on the piston 
Y = velocity of ditto 
'PY — Jcf2finr{2ftnr sin. 9 — u cos. ey sin. esdr 

Let 2 rt w = w ; and smce tan. e = - 

h 

sm. 9 = — ==^ 



Vr+b^ 



cos. 9 = 



Vr-^b' 



=s|3\/ ^+&' 



r b u r ^ b 






, POWER OF SCREW. 306 

r 



/?-+ 6" 



^ _^ =kuib!i(o>b — uf A (suppose). '*' 

Again, if u be the velocity of the ship, and H the effective 
area of the midship section, 

the pressure against the bows = k'H.u' 
But pressure of water on the strip of the scjrew s dr in 
direction of the keel 

= Z; (2 rt ?i r sin. — u cos. ey cos. e s dr 
rb r "" r 



=zkf a — =z= — U — N . — == j3 \/ ^^ + 6' dr 






^ r -\-b 

. ' . whole pressure = k ^ (u>b — uy C ^,.2 d r 

from r = ^ i ^ / -u xa * 

to r=^a :=k!5(.b-.u) A 

Hence kKu"" = k jS (oib — uf A 

B.u' = l5A{^b — uy 
or v/ H w = V /3 A (w 6 — u) 

But «& = velocity of screw in advance ; that is to say,*in 
the direction of the keel = v (suppose). 

V'H.u = \/^A(v-^u) 

or (v^H + v^MT) w = v/jsXv 

V — u 
Let = S (the slip of the screw) 



V ^H + ^/JA >/ H + s/jA 

And P Y = yfc « 6 (co 6 _ w)' A 
= kvji (v — uf A 
==kv^(vSyA 

^k^S'v'A 

. Heyice, so long as the same screw is made use of in the same 
ship, the Indicator horse-power varies as v\ or varies as the 
cube of the speed of the ship. 



306 


MISCELLANEOUS. 


Again, since 


Hw^ = ^A(v — wy 




= /3 A v^ S^ 


. • . 


TY^kKu'v 



If, therefore, the screw be changed in the same ship, the 
horse-power no longer varies as the cube of the speed of the 
ship, but as the square of the speed of the ship multiplied by 
the speed of the screw. Hence the Indicator horse-power will 
in all cases be found to be proportional to the continued product 
of the square of the speed of the ship, the number of revolu- 
tions of the screvj, and the pitch. 

335. To find how far the Slip of a Screw depends on its form 
and Dimensions. 



V 



>/H+^;3A 



r 



bl 



But A = r •. .., d r 



r — 
= a 



= i (r- + b' log., 


r -f b') -f Cor 


= iK + ^'log. 


b^ \ 

' a' 4-67 


= Y(1 +taD.^a 


tan.'- a 
■ '°S- ' 1 + tanJ 







a 
= (1 -f tan.^ a log. 6 sin.^a) 



= - (1 + tan.' a log. ? 1 — COS. a) 

a' f COS. 'a COS.'a ) 

='y |1— tan."-a(cos.^-a+— g— +— 3 h •••)/ 

a' COS.'' a COS." a ... 

= y (1 — sin.- a — sin.^ a — ^ ' 3 *" 



a^ ^ . ^ COS.* a COS.* a . . . . ) 

= — (cOS.^a — sin. a + 3 "f" 



a'cOS.'a, . , . COS.' a ) 

= — 2— (1 — sin.' a. i 4— ^— + 

= ^— i 1 — 1 — COS.'a (l-]_Ac0S.^ + iC0S.*a + • • .) f 



POWER OF SCKEW INVESTIGATED. 307 

a^ COS. 'a f , 1 1 . 1 4 

=i r I 1 — J — ^COS. a — :^COS. a — ... 

+ ^ COS.^ a + ^ COS.* a + ... I * 

a'COS. ^a 2 , , , , 
= J (4+6 COS. a + j^2 COS.* a + 

a^'cos.'a * , 1 * , \ 

= — (1 + ^ COS. a + ^ cos. a + . . . . ) 

Consequently /3 A increases as a increases, and it diminishes 
as a increases ; also it increases as j3 A increases. 

v/H 

But the slip = . tt . — . • the slip increases as jS A 

V ^-r Vjs A ' * * 
decreases, and vice versa. 

Hence, as a general rule, we shall find, caeteris paribus, that — 

(1.) The slip is diminished by decreasing the angle of the 
screw. 

(2.) The slip is diminished by increasing the diameter of the 
screw. 

(3.) The slip is diminished by increasing the length of the 
screw. 

This investigation does not enter into the practical question 
of the effect of the friction of the water on the blades of a screw, 
which increases rapidly with the surface, and affects the result 
obtained in (3). 

336. On the most advantageous Speed for Vessels steaming up 
a River^ or in a Tide-way. 
Let V = velocity of opposing current ; 

X = velocity of the ship through the water ; 
X — V = space passed over in a unit of time. 
Now the horse-power of the ship, or the consumption of fuel 

3 

a or 
in a unit of time oc x^ and = a a;' (suppose) . • . — '- — con- 

X u 

sumption of fuel for every unit of space moved over. 

a X 
Hence = a minimum. 

X — V 
Sos' {X — v) — a;' = (by differential calculus) 
3a; — 3v — x = 

2a; = 3v * 

3 

X = ^v 



dUa MISCELLANEOUS. 

In plain words, the rule is, that the ship should steam half as 
fast again as the opposing current. If v be taken as the speed 
of another ship which we are desirous of overtaking, a similar 
investigation will show that the same result will obtain in tha/t 
case also ; viz., that the rate should be half as fast again as 
that of the ship to be overtaken, when economy is alone consid- 
ered. See Economy of Fuel, by Captain A. Ryder, R.N. 

8§7. On the Motion of Paddle- Steamers in still Water. 

Bef — The slip of a paddle is the difference between the 
rate of the wheel and the rate of the ship, divided by the 
rate of the wheel. 

(The investigations connected with what follows are given 
below.)* 

* Let R = pressure of the fluid against the bows of the vessel when 
moving with the velocity Y. 
R' = the mean pressure of the floats agamst the water, the 
floats moving with velocity U. 
Then it is evident, if the motion be uniform, R = R'. Now R 
depends on the form of the bows and the square of the speed, . • . R 
3^ A^ys, where A^ is constant for the same vessel so long as the 
immersion remains the same. Again, R' = B2(U — Y)^. where B^ 
is some constant depending on the immersion and size of the floats. 
A2Y2 = B^(U — Y)2 
or AY = B(U— Y) 

and r+lBY = BU 



u = (i+^)y ...... (1) 



Again, let P — efiective pressure on the surface of the piston, and 
Vi its velocity ; then, since the motion of the engine is uniform, 
PYi = RU 

= B'{U — YYV 
= A-Y^U 

= A^Y^(l + g)Y 

= ^'(A + B)Y' 

Now P Yi = efiective force of the engine, and this, when divided 
by 33000, gives^bhe horse-power, and consequently the horse-power 



CONSUMPTION OF FUEL IN A GIVEN TIME. 809 

Slip. — So long as the immersion of a ship and the pad- 
dles remains unaltered, the speed of the ship is proportional 
to the speed of the wheel, and therefore the slip is constant 
for all speeds. See equation (1). 

338. Consumption of Fuel in a given time. 
The Tiorse-power of a paddle-steamer is proportional to 
the cube of the speed ; or, in other words, the consumption 
of fuel in a given time, such as a da^y, or an hour, or a week, 
varies as the cube of the speed of the vessel. See equation (2). 
Hence if a ship be at a great distance from port, and the 
fael begin to fail, it would be bad policy to urge the vessel, 
with the idea of reaching her destination. On the contrary, 
unless she meets with opposing winds or tides, the slower 
the engines can move, subject to the condition that no 

ocY^ ......... (2) 

Also, since P Yj =:p Aj Vi, where p =^ pressure of steam per square 
inch, and Ai = the area of the piston, and Ai v^ = volume of steam 
used in a unit of time at the pressure p : hence P Yj is a measure 
of the steam used in a unit of time whatever that unit be, and there- 
fore measures the consumption of fuel in any given time. Conse- 
quently the consumption of fuel in a given time varies as the cube 
of the velocity of the engine or ship. 
, Let Ci = consumption of fuel in one hour 

and N = the number of hours of a voyage between two 

places whose distance is a. 
.-. CiN = whole consumption ; 
and C,NocY3xNxY2x YN. 
But a = YN 

CiNx Y2a (3) 

or the consumption of fuel between two places whose distance is a 
varies as Y^a, where Y is the velocity of the vessel. 

Let U =^ r Yj. where r is the ratio between the velocity of the wheel 
and the velocity of ihe piston, and therefore depends on the nature 
of the machine, so that r Avill be reduced by reefing the wheels, or by 
interposing any multiple gearing between the piston and wheel (as 
is the case in some townig vessels) to increase the velocity of the* 
piston in proportion to that of the wheel. 



310 MISCELLANEOUS. 

Steam is escaping from tlie safety-valve, the more economi- 
cally slie will proceed ; and this will be the effect without 
any consideration of the advantages to be gained by ex- 
pansive working, which will be so much additional. If, 
however, she meet with opposition from wind or tide, it is 
evident no economy will result from letting her lose ground, 
or even by consuming fuel in merely keeping her place ; 
but she should go at a rate half as great again as that at 

Now since P Yi = b'2(U — Y)2U 

^^= J.4-' w 

and by (I) U = (l + A)v 

Also, since P = r A^ Y* 

= rA' ^i-_, = rA^ \ , 

A\- 



(^+b) i^ + i) 



or 



{A + Bf'^' 
Y, = A + B IP 



AB •>J r" • (6) 

Let now r be altered to r', and consequently Y be altered to Y', 
Yi to Ys ; the other quantities remaining the same as before. 

Then 



also 
and 




Xl= I r'^ ^ Y' 

Y, ^^ V- 



0) 



ON BEEFING PADDLE-WHEELS. . 811 

wMch the wind or tide would drive her from the port she 
desires to reach. Thus if she would drift at the rate of 4 
knots, the engines should force her through the water at 
the rate of 6 knots, to make good 2. If at the rate of 6 
knots, the engines should drive her 9, and so on. 

839. On tJw Consumption of Fuel in a Passage between any 
two places. 
By equation (3) we see that the consumption of fuel 
varies as the product of the square of the speed multiplied 
by the distance to be steamed over. Hence, if the con- 
sumption of fuel be C when the speed is Y, and distance in 
miles a ; and the consumpion be Ci when the speed is Yi, 
and distance in miles %, we shall have 
C:C,::Y'xa:Y,'^a,. 

840. On reefing Paddle- Wheels, to obtain greater speed. 

The rate at which the wheel revolves depends on the 
surface of the paddle-boards ; but, provided all the steam 
be used that the boiler can generate, the speed of the ship 
is independent of their size. And therefore, whenever we 
are able to make use of all the steam the engine requires, 
no gain will be effected by diminishing the surface of the 
floats. The only effect would be to increase the slip and 
the consumption of fuel, without obtaining a proportionate 
increase of speed. But, on the other hand, if the wheel 
revolves so slowly that a portion of the steam escapes by 
the safety-valve, then we see by equation (4) and (6) that 
(by diminishing r, that is) by reefing the wheels, the speed 
of the ship is to a small extent increased, on account of tlie 
great increase of speed of the piston (since the former de- 
pends on the effective diameter of the wheels, and the latter 
on the cube of the diameter). So that, the wheels being 
reefed, the effective diameter of the wheels is altered, and the 
piston moves fast enough to enable the engines to consume 
all the steam generated by the boilers, which then acts 
effectively on the ship. 



812 MISCELLANEOUS. 

In reefing the wheels, however, there would be no prac- 
tical gain in the speed of the vessel if the upper edge of the 
lowest board were allowed to come above the surface of 
the water ; for that would have the result of effectually 
diminishing the surface of the float, and therefore would 
increase the speed of the engine without producing any 
effect on the speed of the ship. 

If by means of multiple gearing, or reefing, or otherwise, 
the speed of the ship and engine be increased, it will be 
found (see 7) that the speed of the engine varies as the cube 
of the speed of the ship. 

841. Measure of the Locomotive Performo>nce of Marine 
Steam- Engines. 
Let A be the effective resisting midship section of a steam- 
ship, and V its speed, 

Then the amount of resistance oc Av^ 
and the work to be performed a A^'^ 
Again, since the expenditure of fuel may be approxi- 
mately estimated by the Indicator horse-power, the work 

to be overcome by a unit of fuel is -^ (where I is the In- 
dicator horse-power). 

But if D be the displacement and I the length of the 
ship, We shall have for similar ships, 
D oc Z\- Joe D^ 

and A oc ?2 ^^^ ^ ^ ^j 

Hence A^ oc D^, or A oc Dt 

the measure required is — ^ 

It must, however, be observed, that this formula does 
not strictly apply to ships of different build, or in compar- 
ing different screws in the same shi'p, or with different 
grades of expansion. 



PISTON AND CRANK MOTIONS. 



313 




342. To find the Angle the Cranh has 
moved through when the Piston is at 
a given distance from the top of ih^ 
Stroke. 

Let P be tlie position of the 
crank; PA tlie connecting-rod 
at the distance B A from its 
highest point B ; 
and let OP = a;PA = c 

BA=i^; ZP0A = 8 
Then OB=:c — a 
And by Trigonometry, 



o«.|=4 



-J 
-J 



(0 P + A + P A) (OP -f A - 


-AP) 




4 . OP . 


OA 




(a + c- 


-a -\- X -{■ c) {q 


j+c — 6^4- 


x — c) 



. (c — a -\- x) 



{2 c -\- x) .X 



4a(c — -a-\-x) 

a 

Hence, having given c, a, and x, we may find ^ and there- 
fore d. 

343. To find the amount of Work developed by a Crank in 
half a complete devolution, if a constant pressure act verti- 
cally at the lower end of the Connecting-rod. 

Let the crank P (in any position) make an angle P A 
= e with the vertical line, and P A = <j> 
P = a, P A == c. 

Then if P be the upward pressure at A, let R be the force in 
the direction of the connecting-rod ; 



814 



MISCELLANEOU! 



resolving E horizontally and vertically, we have 
R COS. 9 = P (1) 



and the moment of the force to turn the crank = Ro sin. e + t 



. =Pa 



sin. 9 -^^ 

COS. t 



and the amount of work while moving through an angle d 6 
_ sin. e -f A , 
cos. 4> 
. • . the work performed while the piston is ascending 

J CO 



de 

COS. ^ 

taken between the limits 5=0 and e = ^ ; 

„^ _ p r sin. e COS. ^ -f COS. d sin. 4) 



Pa 



/< 



COS. t 

sin. * 
sm. e -\ cos. e)de 

COS. ^ ^ 



<;<? 



But sin. t = ~ sin. 5 ; 
c 




a . 

- sm. 6 COS. ^ 
c 

.-. W=Pft f Csin. 0+ 


do 


Jl--sm. 5^ 


c 1 a' 
= P a ( — COS. ^1 — — sin. ^ i 

= 

« rt = .P . 2 a 


? ) + cor. 



which is the same as would have been obtained if the power 
had acted through the vertical diameter without the inter- 
vention of a crank. It is evident that this result might 
have been arrived at immediately by the principle of vir- 
tual velocities ; but since it is frequently imagined power 
is lost by the use of a crank, it has been thought advisable 
to give an independent investigation. 



LENGTH OF THE RADIUS-BAR. 



315 



314. To find the length of the Madius-har in a side-lever 
Engine, 

Let A B be the 
radius-bar ; B C 
the parallel-mo- 
tion side-rod ; C 
that portion of 
the side-lever be- 
tween (the 
main centre) and 
BC. 

Let A B = a;; 
B'c=a; C'c=6; 
C0 = 2/; Z B' 
AB = e; Z CcC' = 4; C'OC=t. 

Now we have x cos. 9 -f a sin. 4- = a? (1) 

also y cos. ^ -{-h sin. 4' = 2/ (2) 

and X sin. e + {a -\- b) = {a-^h) cos. 4 + ?/ sin. <j> (3) 

And (1) let d, 4., and t be small angles, which is the case 
where the radius-bar is long. 

Then from these equations we get 

x\l — ^^-{-a^^x] ova^=^B' 
2/(1 — |')+64=2/; or6^=|t^ 




' also 

and 

Hence 

and 



X d •\- {a -\- b) = {a -\- h) + 2/ 1 ; ox xd =y^, 
a X d" 
b y ^' 



f = ^^ =^ . oT AB': C'0::C'c:cB'. 
?/ a; a? ' 

(2.) Let 5 be large, and 4 and ^ small ; which is the case 
where the radius-bar is short. 
Then, as before, 



also 
and 



X cos. e-\- a^ — o:- 
X sin. d -\- {a -\-h) — (a -f 6) + y t 



« 



e 



816 MISCELLANEOUS. 







X COS. 9 = X — 


a^ 




also 




H = f 






and 




X sin. e wm^y^ 










XQO^.e = X — 


b^ 2 




. • . X 


' (sin.^ 


6 -\- COS. V) = x^ — -^xy^ 


. «' . 

'+6-^ 


f + ^/'f 


Hence 




ax , «' t 

X ^b a t' 
2/"'a''"6*4' 




• 


But the 


angle 


described by the side-lever is usually about 


20° 








« 


Hence 




^ = 9^^^4=324 = 


= -0304 




and . • . 




X b a 

-=-+ -0304 7 
y a b 







the correction to the first approximation, being "0304^. 



345. To find the amount of Work <ione in the up and down 
stroke of an Air-pump {neglecting friction^ etc) 

(1.) Suppose the pump fitted with an air-tight delivery- 
valve, and that there is a vacuum above and below the air- 
pump bucket. • • 
Let B = the area of the bucK'et. 
h = the length of stroke. 

b — distance from surface of water in the bucket to the 
cover of the air-pump. 
h — b = height of water; in the bucket. 
= specific gravity of ditto. 
w = weight of waiter to be lifted = a (Ji — 6) B. 
This will be raised throagh a space 6, when the delivery -valve 
will open. 

Let the top of the air-pump be at a depth I below the sur- 
face of the water, arid k the height of water due to the atmos- 
pheric pressure. » 



LOSS FROM BLOWING-OUT. 31t 

. • . the mean pressure on the bucket after the delivery- valve 

opens is ff b( Z + ^ -| — ), and the space to be passed over 

is /i — b. 

• . the whole work is a {h — b)Bb + nB (^l -i- k -{- -^) 
(h^b) 

= ,(h^b)B(l+k + ^-^b) 

-K^-^^ + '-t") 

and there is no work in the down-stroke. 

2. Suppose the air-pump not to have a delivery-valve, 

thin the mean pressure in the up-stroke is aB ( l-i- k -\- -\i 

and the space passed over is h. 

. • . the work in the up-stroke is aB ll-[- k -}- -jh. 

Again, in the down-stroke, the mean pressure is <j B (Z-f^+^jj 

and the space passed through till the water is reached by the 
bucket is b; 

. • . the negative work in the down-stroke is aB(l-{-k+ -jb. 

Hence the whole work in the up and down stroke is 

aB(l-{-k-{-^ h^aB Q^k+^ b=6B(h—b){l-j-k)+aB^~- 

= .B (h-b) (ik^k^^-^^ =^w(l + k +^), • 
precisely the same as in the former case. 



S4t6. To determine the amount of Fuel lost by the process of 
Blowing-out. 

Let X = the number of gallons blown-out in a given time. 

2/ = " of water evaporated. 

. •. a; -f i/ = quantity entering as feed. 
Let t = temperature of feed- water. 

T = " of water in boiler. 

. • . (1212 — t) y = quantity of heat expended in the forma- 
tion of steam. 



318 MISCELLANEOUS. 

(T — ^) a? = quantity expended in heating water to be 
blown-out. 
.-. (1212 — t) y -{- {T — t) X = whole quantity of fuel ex- 
pended. 
If, therefore, Q be the amount of fuel lost per cent in blow- 
ing-out, 

Q_ (T — t)x 

100 (1212 — 2/ + {T^ — t)x 
from which formula the last column in Table D may be calcu- 
lated. 

347. To determine the best Temperature for the Condenser of a 
Steam-Engine. 
The best temperature is evidently that in which the 
residue of work done (after making allowance for the duty 
of the air-pump) by the heat requisite to raise the water 
from the temperature of the condenser to that of the boiler 
may be a maximum. 

Let therefore t^ = temperature of injection-water. 

a°= amount of heat in a unit of steam (1212°). 
a?° = the temperature of condensation. 
P = mean pressure on piston. 
p = pressure of uncondensed steam. 
. • . P — p = effective pressure. 

Again, let A = area of piston. 

I = length of stroke. ^ 
n I = height to which the air pump has to raise 

the water. 
w = weight of cylinderful of steam. 
X = weight of injection-water admitted to con- 
dense it. 
. • . (P — p)l A = work done by steam in one stroke. 
(w-\-^)nl = work expended by air-pump. 
w {(P — x'^) = amount of heat expended. 

(F—p)lA — (w + X)nl 

^-^ — ; ^-T — = a max. 

w{a — X) 

or (P— p)A— (w;-fX)n 

^^ ^-^ ^^- ^-= a max. 

a — X 

aw-{-Xt , «^v 



BEST TEMPERATURE OF COXDEXSER. 319 
w (a — .t) 



X 



w (a — 

and . • . = a max. 

Hence, differentiating, we get 
( dp ' a — It 1 nw{a — t) 

i- ^-^ + '""' w^'\ « - ^+p - p ^ - ^izr =" 

dp nw (a — t) /a — x \ 

aod 2- A (.-.) - P-^, A ^ - (;-:^y — ^ nearly. 

Bat by Tredgold's formula, 

1/100 + ^x^ 



1 /^lUU -f- X \^ 



dp__ S / 100 + ^ \' _ 2 /' 100+ ^ \° 
d^ ~ m V 177 / "~59V 177 / 
/iUU-f-.37\^ =r- nw (a — /) 

59 (^m-) «— -P-P-r -J^^iy 



„ 1 /100 + .^x' =r- nw(a~t) (a — x) 

Hence ' \ ^ n. i^ ^ 



59 ?2iy (a — t) (a — x) 



(x-ty 



/lO^A- sc X ' 59 (P — p) 59 nw (a — t) 

59 nw {a — t) 
A 
.. r,r-n-=^^ 100"+^V __ 59(P-p ) • • • • (1) 



V 177 y ■" a — , 



From whicli equation we must determine x approxi- 
mately. To do this, we must first substitute for x on tlie 
right-hand side of the equation whatever we consider to be 
the most probable value ; and solving the equation on this 
supposition, we shall get a corresponding value of x on the 
left-hand side. ISTow, from the form of the equation, we 
see, that if we substitute too high a value at first, we shall 
get too low a result, and vice versa: hence the true value 
must be somewhere between the two. Let, therefore, a 
mean of the assumed and resulting value bo taken, which 
21 



820 MISCELLAXEOUS. 

substitute again as an assumed value, to get a closer ap 
proximation, and so on. 

Now in (1) w = the weight of a cylinderful of steam. 

62*5 ** 
But the weight of a cylinderful of water =-——l A in lbs. 

144 

A being expressed in square inches. 

Hence by M. de Pambour's formula, 
62-5 

where p^ = the pressure at the end of the stroke. 
62-5 X 59 , , ^ , ,, , ,, 

Hence (x — tY = -^^ , 1 'FK~rs ^~ 

^ -' /100 4-^\ 59 (P — p) 

V 177 ) " 



a — X 

\nl(a + bv,) (i 
or a; = ^ + 5-061 



?2Z(a + 6pi) (a — t) 



/ lOO + ^ \ ' 59(P— p ) 
V 177 / "~ a — x 

Again, ?iZ = height due to the pressure on the air-pump, 
= 30 + 7i nearly, since the pressure of the atmosphere = 34 
feet, and we may reckon the deficiency of the vacuum in the 
condenser at 4 feet ; also h is the height from the bottom of 
the air-pump to the surface of the water outside the ship. 



-f 5-061nJ 



(30-f 70(a + 6pO(a — 
.100 4- ^\' 59 i^—p) 



V 177 / a — X 

The 'most suitable temperature, therefore, depends on 7t,pi, 
and t, as we stated in our general principles, art. 239. 
As an example, let t = 60° 
h= 4 
p,= 14 
p.nd X = 100° 

We get as a result x= 83'25 
and . • . taking the mean, 83-25 

100-00 

2)183-25 
91-62 



QUALITIES OF FUEL. 321 

Again, substituting this value, we get x = 8G-59 ; 
and taking the mean, 91*62 

86-59 



2)lt8'21 



x = 89-10 



848. On the Qualities of Fuel. 

The following remarks on the subject of fuel are ex- 
tracted from the result of some researches undertaken by 
the direction and at the cost of the Admiralty, at the Mu- 
seum of Practical Greology, by Sir Henry de la Beche and 
Dr. Lyon Playfair. The nature of our present work re- 
quires little more than the mere result of the investigations ; 
and those who want fuller information must refer to " Ee- 
ports on the Coals suited to the Steam Navy, by Sir Henry 
de la Beche and Dr. Lyon Playfair." 

Experiments necessary to ascertain the true practical 
value of coal involve a large series of observations, ex- 
tended over a considerable period, and directed to special 
objects of inqury. The qualities for which particular kinds 
of fuel are pre-eminent being so varied, it is impossible to 
deduce general results from a limited series of observations. 
Even in the one economical application of coals, their evap- 
orative value, or their power of forming steam, one variety 
of coal, which may be admirably adapted, from its quick 
action for raising steam in a short period, may be far ex- 
ceeded by another variety, inferior in this respect, but 
capable of converting a much larger quantity of water into 
steam, and therefore more valuable in the production of 
force. A coal uniting these two qualities in a high degree 
might still be useless for naval pi^rposes on account of its 
mechanical structure. If the cohesion of its particles be 
small, the effect of transport, or the attrition of one coal 
against another by the motion of a vessel, might so -far pul- 
verize it as materially to reduce its value. Even supposiug 
the three qualities united, rapidity and duration of action 



MISCELLANEOUS. 



with considerable resistance to breakage, there are many 
other properties which should receive attention in the se- 
lection of a fuel, without the combination of which it might 
be valueless for our steam-navj. 



349. Weight of Coal when used as Fuel. 

There is an important difference existing between varie- 
ties of coals in the bulk or space occupied by a certain 
weight. For the purposes of stowage-room this cannot be 
ascertained by specific gravity, alone, because the mechani- 
cal formation of the coal may enable one of less density to 
take up a smaller space than that occupied by another of a 
higher gravity. This is far from an imaginary difference, 
being sometimes as great as 60 per cent., and not unfre- 
quently 40 per cent. The mere theoretical determination 
of the density of coals would therefore give results useless 
fori^practice. The space occupied between two varieties of 
coals, often equally good as regards their evaporative value, 
differs occasionally 20 per cent. ; that is, where 80 tons of 
one coal could be stowed, 100 tons of another of equal evap- 
orative value might be placed, by selecting it according to 
its mechanical structure. These facts are mentioned merely 
to show that a hasty generalization should not be made, 
and to account for drawing, attention to these various points 
as a means of preventing the selection of a fuel from any 
one quality. 

350. Patent Fuels. 

Yarious compositions, under the name of Patent, or Ar 
tificial Fuels, have been experimented on, and the results 
entered in the accompanying Tables. Patent fuels are usu 
ally made up in the form of bricks, and would therefore 
be very convenient for stowage, if sufficient time could be 
spared for packing them when they are received on board 
This, however, is rarely the case either in vessels of wai 
or packets, except perhaps on leaving a home port. Owing 
then, to their low specific gravity, they occupy, on ordi 



PATENT FUELS. 323 

narj occasions, a greater space per ton tlian any species of 
coal. They are usually composed of a mixture of coal- 
dast and tarry or bituminous matter; water, and occa-. 
sionally other ingredients, being used for cementing the 
compound. 

Warlich's fuel is composed of one ton of Graigola or Ee- 
solven coal-dnst, containing on an average 16 gallons of 
water, intimately mixed with 16 gallons of coal-tar. 

Holland and Green's fuel is of the following composition : 

Lime 100 parts 

Grypsum 17 " 

Alum 17 " 

Common salt 17 " 

Aluminous clay 28 " 

Screenings of Newcastle coal . . . 2240 " 
Mixed with about 20 gallons of pure water. 
But fuel containing much foreign matter in its composi- 
tion generally produces a large amount of clinker and ash. 
The evaporating powers of the other five patent fuels rank 
high as compared with that of the coals experimented on. 
In general, however, they do not light readily ; they emit 
great quantities of black smoke, and produce much soot. 

To remedy these defects, and as it has been repeatedly 
stated by eminent engineers that the value of fuel for steam 
purposes depends on the quantity of fixed carbon it con- 
tains, experiments were made at the suggestion of the late 
First Lord of the Admiralty to ascertain how far mixtures 
of anthracite with more bituminous coals were likely to 
prove advantageous in the manufacture of artificial fuel. 
The experiments were undertaken at Swansea, the propri- 
etors of Warlich's Patent Fuel Works having allowed the 
use of their apparatus for the purpose. It was found, how- 
ever, that the advantages of these additions were not such as 
to recommend their adoption. The cementing-tar, though 
partially carbonized by the heat of the coking-ovens, in 
which the prepared fuels are heated, was so much more 
combustible than the dense and slowly igniting anthracite. 



824 MISCELLAXEOUS. 

that the latter remained after the combustion of the former; 
and therefore either accumulated on the bars, obstructing 
the draught, or, falling through the grate, escaped combus- 
tion. If thrown again on the fire, it choked the air-way, 
and impeded the proper action of the fuel. The evapora- 
tive power of the fuels thus prepared was certainly found 
to increase in proportion to the addition of fixed carbon ; 
but this would appear to arise from the fuel then assuming 
more of the characters of the anthracite; or coke, from which 
it was made. The results of the experiments pointed to 
the necessity of keeping a uniform character in the fuels 
manufactured. 

351. Effects of Stoioage upon Coals. 

It is of much importance in an economiical inquiry on 
coals, to obtain exact information as to the effect likely to 
be produced upon them by stowage and continued exposure 
to high temperature, not only as reg*ards their deteriora- 
tion, but also as to the emission of dan'gerous gases by 
their progressive changes. The retention of coal in iron 
bunkers, if these are likely to be influenced by moisture, 
and especially when by any accident wetted with sea- water, 
will cau.se a speedy corrosion of the iron, with a rapidity 
proportionate to its more or less efficient protection from 
corroding influences. This corrosion seems due to th3 
action of carbon or coal forming with the iron a voltaic 
couple, and thus promoting oxidation. The action is simi 
lar to that of the tubercular concretions which appear on 
the inside of iron water-pipes, when a piece of carbon, not 
chemically combined with the metal, and in contact with 
saline water, produces a speedy corrosion. Where the 
" make" of iron shows it to be liable to be thus corroded, 
a mechanical protection is generally found sufficient. This 
is sometimes given by Eoman cement, by a lining of wood, 
or by a drying oil driven into the pores of the iron under 
great pressure. 

Kecent researches on the gases evolved from coal prove 



COAL SUITED TO STEAM-XAYIGATION. 825 -, v ^ 

that carbonic acid and nitrogen are constantly mixed with 
the inflammable portion, showing that the coal must still 
be uniting with the oxygen of the atmosphere, and entering 
into further decay. 

852. Decay' of Voals. 
Decay is merely a combustion proceeding without flame, 
and is always attended with the production of heat. The ^ ' 
gas evolved during the progress of decay, in free air, con- 
sists principally of carbonic acid, a gas very injurious to 
animal life. It is well known that this^ change in coal 
proceeds more rapidly at an elevated temperature, and 
therefore is liable to take place in hot climates. Dryness 
is unfavorable to the change, while moisture causes it to 
proceed with rapidity. When sulphur or iron pyrites (a 
compound of sulphur and iron) is present in considerable 
quantity in a coal still changing under the action of the 
atmosphere, a second powerful heating-cause is introduced, 
and both acting together may produce what is termed spon- 
taneous combustion. The latter cause is in itself suf&cient, 
if there be an unusual proportion of sulphur or iron pyrites 
present. The best method of prevention in all such cases 
is to insure perfect dryness in the coals when they are 
stowed away, and to select a variety of fuel not liable to 
the progressive decomposition to which allusion has been 
made. ^ 

853. Qualities of^ Goals suited to Steam- Navigation. 
The various qualities of coal on which its value, as far 
as steam-navigation is concerned, depends, are thus summed 
up: 

1. The fuel should burn so that steam may be raised in 
a short period, if this be required ; in other words, it should 
be capable of a quick action. 

2. It should possess high evaporative power ; that is, be 
capable of converting much water into steam with a small 
consumption of fuel. 



326 MISCELLANEOUS. 

. 3. It should not be bituminous, lest so much, smoke be 
generated as to betray the position of ships-of-war, when 
it is desirable that this should be concealed. 

4. It should possess considerable cohesion of its parti- 
cles, so that it may not be broken into too small fragments 
by the constant attrition which it may experience in the 
vessel. 

5. It should combine a considerable density with such 
mechanical structure that it may easily be stowed away in 
small space ; a condition which, in coals of equal evapora- 
tive values, often, involves a difference of more than 20 per 
cent. 

6. It should be free from any considerable quantity of 
sulphur, and should not progressively decay ; both of which 
circumstances render it liable to spontaneous combustion. 

It never happens that all these conditions are united in 
one coal. To take an instance, anthracite has very high 
evaporative power ; but not being easily ignited, is not 
suited for quick action : it has great cohesion in its parti- 
cles, and is not easily broken up by attrition ; but it is not 
a caking coal, and therefore would no't cohere in the furnace 
when the ship rolled in a gale of wind : it emits no smoke ; 
but from the intensity of its combustion causes the iron of 
the bars and boilers to oxidate or waste rapidly away. 
Thus, then, with some prctcminent advantages, it has dis- 
advantages which, under ordinary circumstances, preclude 
its use. 



The following abstract of the working Tables will give 
a general view of the relative value of the coals experi- 
mented upon. It must not, however, be taken as the exact 
expression of their values without a reference to the de- 
tailed description of each experiment as given in the "Ee- 
port" from which these extracts are made. 



POWEK AND DUTY OF COALS. 



,07 



Table I. Power and Duty, etc., of various Coals. 



Locality or Name of Coal. 



WELSH. 

Aberaman Merthyr 

Ebbw Vale 

Thomas's Merthyr 

Duffryn 

Nixon's Merthyr 

Binea 

Bedwas , 

mil's Plymouth Work 

Aberdare Co.'s Merthyr 

Gadly Nine-feet Seam 

P.esolven 

Mynydd Newydd 

Abercarn 

Anthracite, Jones and Co 

Ward's Fiery Vein 

Neath Abbey 

Graigola 

Gadly Four-feet Seam 

Mrtchen Rock Vein 

Birch Grove, Graigola 

Llynvi 

Cadoxton 

Oldcastle Fiery Vein 

Vivian and Sons' Mirfa 

Llangeunech 

Three-quarter Rock Vein 

I'entrepoth 

Cwm Frood Rock Vein 

Cwm Nanty Gros 

Brymbo Main 

Vivian and Sons' Rock Vawr... 

Coleshill 

Byrmbo Two-yard 

Rock Vawr 

Porth-mawr 

Pontypool \ 

Pentrefelen 



NEWCASTLE. 

Willington 

Andrews House Tanfieid 

Bowlen Close 

Ilaswell Wallsend 

Newcastle Hartley 

Hedley's Hartley 

Bates' West Hartley 

West Hartley Main 

Buddie's West Hartley 

Hastings' Hartley 

Carr's Hartley 

Davison's West Hartley 

North Percy Hartley 

Haswell Coal Co.'s Steamboat 

Wallsend 

Per went water Hartley 

Ihoomhill 

Original Hartley 

Cuwpcn and Sidney's Hartley... 



A. 

l'0-75 
10-21 
10-16 
10-14 
9-96 
9-94 
9-79 
9-75 
9-73 
9-56 
9-53 
9-52 
9-47 
9-46 
9-40 
9-.38 
9-35 
9-29 
9-23 
9-22 
9-19 
8-97 
8-94 
8-92 
8-86 
8-84 
8-72 
8-70 
8 42 
8-36 
8-08 
8-0 
7-85 
7-68 
7-53 
7-47 
6-36 



9-95 
9-39 
9-38 

8-87 
8-23 
8-16 
8-04 
7-87 
7-82 
7-77 
7-71 
7-61 
7-57 

7-48 
7-42 
7-3 

6-82 
C-79 



B. 

48-9 
53-3 
53.-0 
53-22 
51-7 
57-03 
50-5 
51-2 
49-3 
54-8 
f58-66 
56-33 
50-3 
58-25 
57-433 
59-3 
60-166 
51-6 
48-1 
51-0 
53-3 
58-1 
50-916 
47-9 
56-93 
56-388 
57-72 
55-277 
56-0 
47-0 
48-9 
53-0 
47-9 
55-0 • 
53-3 
55-7 
66-166 



53-2 
52.1 
50.6 
47-4 
50-5 
52-0 
50-8 
48-9 
50-6 
48-5 
47-8 
47-7 
49-1 

49-5, 
50-4 
52-5 
49-1 

47-9 



^ 



C. 

81-91 

78-81 

82-29 

82-72 

82-29 

81-357 

82-6 

84-78 

81-73 

83-16 

82-354 

81-73 

83-22 

85-786 

83 85 

83-57 

81-107 

82-79 

80-91 

84-85 

80-35 

85-97 

80-42 

81-04 

81-85 

83-60 

81-73 

78-299 

79-859 

81-10 

81-16 

80-483 

80-04 

80-21 

86-722 

83-35 

84-726 



79-87 
78-86 
79-87 
80-23 
80-27 
81-79 
78-17 
78-86 
77-11 
78-04 
78-23 
78-36 
78-29 

70-36 
78-79 

77-9SS 



D. 

45-80 

42-26 

42-26 

42-09 

43-32 

39-24 

44-32 

43-74 

45-43 

40-87 

38-19 

39-76 

44-53 

38-45 

39-00 

37-77 

37-23 

43-41 

46-56 

43-92 

42-02 

38-55 

43-99 

46-76 

39-34 

39-72 

3S-80 

40-52 

40-00 

47-65 

45-80 

42-26 

46-76 

40-72 

42-02 

40-216 

33-85 



42-10 
42-99 
44-26 
47-25 
44-35 
43-07 
44-10 
45-80 
44-09 
46-18 
46-86 
46-96 
45-62 

45-25 
44-44 
42.67 
45-62 

-10-76 



45-0 
57-5 
56-2 
64-5 
51-2 
54-0 
64-0 
74-5 
76-0 
35-0 
53-7 
54-5 
68-5 
46-5 
50-0 
49-3 
68-5 
52-5 
59-0 



57-7 
54-0 
53-5 
52-7 
46-5 
72-5 
55-7 

70-5 
62-0 
79-5 
65-5 
62-0 
57-5 
52-7 



43-00 

3S-5 
73-0 
78-5 
85-5 
69-5 
79-0 
80-0 
75-5 
77-5 
76-5 

eo-0 

79-5 
63-5 
65-7 
80-0 
74-0 






351-2 

411-66 

308-0 

300-S 

406-8 

457-50 

413-3 

404-5 

344-3 

402-9 

423-5 



G. 

13-3 



460-22 




520-8 


3-9 


409-32 




511-4 


5-7 


486-95 




476-96 




531-6 


7-5 


489-5 


9-8 


517-3 


6-0 


390-25 


... 


470-69 




480-00 


20-0 


409-37 


... 


529-90 




546.1 


19-2 


441-48 




400-0 


11- 6 


488-75 


12-4 


507-50 


28-6 


399-50 


36-0 


344-16 


34.7 


464-30 


... 


421-25 


18-0 


373-22 


... 


486-86 




381-50 




379-80 




404-16 




435-83 


16-7 


492-50 


30-1 


406-41 




441-66 


19-5 


307-5 


38-0 


347-44 




250-40 




247-24 


... 



6-6 
0-5 
17-0 
14-4 
1-4 
2-8 
5-9 
1-7 
5-0 
2-1 



291-8 9-8 

451-1 I 28-3 
397-78 
4-28-4 10-1 

o50-4 a-7 I 



?,9) 



POWER AXD DUTY OF COALS. 



Table I. [continued) 



Locality or Kame of Coal. 



DERBYSHIRE. 

Eaii Fitz William's Elsecar 

Hoyland and Co.'s Elsecar 

Earl Fitzwilliam's Park Gate 

Butterly Co.'s Portland 

Butterly Co.'s Langley 

Stavely 

Loscoe Soft 

Loscoe Hard 

LANCASHIRE. 

Ince Hall Co.'s Arley 

Hoydock Little Delf 

Balcarres Arley 

Blackley Hurst 

Ince Hall Pemberton Yard 

Haydock Rushy Park 

Moss Hall Pemberton Four-feet. 

Haydock Higher Florida 

Ince Hall Pemberton Four-feet.. 

Blackbrook Little Delf. 

King 

Rushy Park Mine 

Blackbrook Rushy Park 

Johnson & Wirthington's Rushy 

Park ;. 

Laffak Rushby Park 

Balcarres Haigh Yard 

Haydock Florida Main 

Wigan Foui'-foet 

Ince Hall Pemberton Five-feot... 

Cannel (Wigan) 

Ince Hall Co.'s Furnace Vein 

Balcarres Lindsay 

Caldwell & Thompson's Rushby 

Park 

BalcaiTes Five-feet 

Moss Hall Pemberton Five-feet.. 

Moss Hall Co.'s New Mine 

Caldwell and Thompson's Higher 

Delf 

Johnson and Wii'thington's Sir 

John 

SCOTCH. 

Wallsend Elgin 

Wellewood 

Dalkeith Coronation Seam 

Kilmarnock Skerrington 

Fordel Splint 

Grrangemoutli 

Eglinton 

Dalkeith Jewel Seam 

IRISH. 
Slievardagh Irish Anthracite 

VARIOUS. 

Coleshill Co.'s Bagilt Main 

Ewloe 

Ibstock 

Lydney (Forest of Dean) 

Conception Bay, Chili 



c ^ 



A. 

8-52 
8-07 
7-92 
7-92 
7-80 
7-26 
6-88 
6-32 



9-47 
9-13 

8-83 
8-81 
8-78 
8-74 
8-o2 
8-39. 
8-34 
8-29 
8-17 
8-08 
8-02 

8-01 
7-98 
7-90 
7-83 
7-77 
7-72 
7-70 
7-47 
7-44 

7-34 
7-21 
7-13 
7-04 

6-85 



8-46 
8-24 
7-71 
7-66 
7-56 
7-40 
7-37 



9-85 



8-33 
7.02 
6-91 
8-52 
5-72 



B. 

47-2 
48-2 
47-0 
47-1 
47-8 
49-9 
44-8 
5-9 



47-6 

44-9, 

50-5* 

48-0 

48-0 

49-3 

47-3 

49-5 

51-8 

51-0 

50-8 

47-0 

55-3 

50-0 
52-6 
50-8 
48-0 
53*4 
51-8 
48-3 
49-3 
51-1 

.47-5 
49-0 
48-3 
4S-4 



54-6 

52-6 

51-66 

44-7 

55-0 

54.25 

52-0 



62-8 



49-6 
50-4 



C. 

SO-85 
82-16 
81-79 
81-16 
78-86 
79-79 
SO-17 
79-60 



79-36 
78-42 
78-17 
78-90 
84-10 
82-54 
78-48 
75-99 
79-60 
78-16 
81-10 
80-04 
80-15 

80-10 
84-07 
80-10 
79-04 
75-49 
79-17 
76-80 
81-98 
78-61 

76-29 
79-11 
80-04 



79-48 
81-73 

78-611 

78-611 

77-42 

78-611 

80-48 

79-84 

79-672 

99-57 



79-17 

79-54 

80-54 

80-046 

80-54 



D. 

47-45 
46-47 
47-65 
47-55 
46-86 
44-88 
50-00 
48-80 



47-05 
49-88 
44-35 
46-66 
46-66 
45-43 
47-35 
45-25 
43-24 
43-92 
44-09 
47-65 
40-50 

44-80 
42-58 
44-13 
46-66 
41-94 
43-24 
46-37 
45-43 
43-83 

47-15 
45-71 
46-37 
46-28 

46-28 

43-41 



41-02 
42-58 
43-36 
50-11 
40-72 
40-13 
43-07 
44-98 



45-16 
44-44 
47-35 
41-14 



E. 

77-0 
82-5 
78-0 
89-0 
84-5 
88-5 
02-0 
86-0 



73-5 
66-5 
76-0 
65-0 
75-5 
77-0 
71-5 
74-0 
74-5 
61-5 
78-5 
67-0 
80-5 

69-0 
75-5 
80-0 
81-5 
75-0 
71-5 
95-0 
71-5 
70-0 

76-0 
44-5 

78-5 
76-5 

77-0 

82-0 



64-0 
800 
8S-2 
63-5 
63-0 
69.7 
79-5 
85-7 



79-0 
84-0 
62-0 
55-0 






F. 

412-70 

372-91 

393-75 

487-08 

398-69 

466-2 

49-11-06 

431-42 



487-29 

532-91 

454-1 

500-8 

461-25 

4ci-eo 

480-00 

4t;7-50 

497-39 

440-4 

395-41 

419-1 

4bl-2 

454-5 

435-0 

398-3 

4-22-50 

414-79 

495-20 

381-1 

435-21 

431-5 

449-79 
489-5 
417-18 
422-08 

484-28 

360-7 



43.r77 

438-5 

370-08 

470-83 

464-98 

380-4 

406-2 

355-18 



473-18 



461.25 
363-95 
454-16 
487-19 
4-25-0 



u. 

6-6 

1-7 

none 

10-3 

10-0 

12-6 

8-4 

8-5 



10-7 

9.6 

11-0 

12-2 

10-8 

7.8 

7-1 

13.2 

2.1 

none 

47-1 

2-7 

-1 

8-6 
5-1 
26-4 
9-0 
37-6 
20-4 
21-1 
•25-3 
22-3 

5.1 

21-8 
31-9 
34-2 



28-5 
*6-4 



5-7 

4-4 

141 



MEAN COMPOSITION OF VARIOUS COALS. 



329 



Table I. {continued.) 





-s . 


% 


^ 


flo 


c 








-S'5 


■g 




^a 




1 1 




Locality or Name of Coal. 




1^ 


if 


3 ~~- 


1 

> 




a. 




'oV, 




o-^ 




« 


« ^ 


O 




fa 

§2 


■g 






^ 




<« 


1 


bO 




2.2 


a 


« o 






^- 


^ 


^ 


Mo 


o 


5 


1 


PATENT FUELS. 


A. 


B. 


c. 


D. 


E. 


F. 


G. 


"Warlich's Patent Fuel 


10-36 
1003 

9-58 
8-92 
8-53 
7-59 


69-05 

65-6 

61-1 

65-08 

65-3 

64-8 


72-248 

73-86 

74-73 

68-629 

71-124 

81-23 


32-44 
34-14 
36-66 
34-41 
34-30 
34-56 




457-84 

483-95 

409-1 

418-89 

549-11 

470-0 


28-2 
38-7 

87-6 






^\ vl'iiu's 


Bell's 







Table II. Mean Composition of average Samples of various Coals. 



Locality or Name of Coal. 



WELSH. 

Aberaman Merthyr 

Ebbw Vale 

Thomas's Merthyr 

Duft'ryn 

Nixon's Merthyr 

Binea 

Bedwas 

Hill's Plymouth Work 

Aberdare Co.'s Merthyr 

Gadly Mne-feet Seam 

Resolven 

Mynydd Newydd 

Abercarn 

Anthracite, Jones & Co 

Ward's Fiery Vein 

Neath Abbey 

Graigola 

Gadly Four-feet Seam 

Machen Rock Vein 

Birch Grove, Graigola 

Llynvi 

Cadoxton 

Oldcastle Fiery Vein 

Vivian and Sons' Merthyr 

Llangennech 

Three-quarter Rock Vein 

Pentrepoth 

Cwm Frood Rock Vein 

Cvvm Nanty Gros 

Byrmbo Main 

Vivian and Sons' Rock Vawr... 

Coleshill 

Byniibo Two-j'^ard 

Rock Vawr 

Porth-mawr 

Pontvpiol 

Pontrefelin 



E ■ 

iS o 

1 


1 


1 
-a 


1 


u 

3 
Si 
P< 

"s 


1 

o 


A. 


B. 


c. 


D. 


E. 


F. 


1-305 


90-94 


4-28 


1-21 


1-18 


0-94 


1-275 


89-78 


■5-15 


2-16 


1-02 


0-39 


1-30 


90-12 


4-33 


1-00 


0-85 


2-02 


1-326 


88-26 


4-66 


1-45 


1-77 


0-60 


1-31 


90-27 


4-12 


0-63 


1-20 


2-53 


1-304 


88-66 


4-63 


1-43 


0-33 


103 


1-32 


80-61 


6-01 


1-44 


3-50 


1-50 


1-35 


88-49 


4-00 


0-46 


0-84 


3-82 


1-31 


88-28 


4-24 


1.66 


0-91 


165 


1-33 


86-18 


4-31 


1-09 


0-87 


2-21 


1-32 


79-33 


4-75 


1-38 


5-07 


Included 


1-31 


84-71 


5-76 


1-56 


1-21 


in Ash. 
3-52 


1-334 


81-26 


6-31 


-77 


1-86 


9-76 


1-375 


91-44 


3-46 


0-21 


0-79 


2-58 


1-349 


87-87 


3-93 


2-02 


0-83 


Included 


1-31 


89-04 


5-05 


1-07 


1-60 


in Ash. 


1-30 


84-87 


3-84 


0-41 


0-45 


7-19 


1-32 


88-56 


4-79 


0-88 


1-21 




1-297 


71-08 


4-88 


•95 


1-37 


17-87 


1-360 


84-25 


4-15 


-73 


-86 


5-58 


1-28 


87-18 


5-06 


0-86 


1-33 


2-53 


1-378 


87-71 


4-34 


1-05 


1-75 


1-58 


1-289 


87-68 


4-89 


1-31 


0-09 


3-39 


1-299 


82-75 


5-31 


1-04 


-95 


4-64 


1-312 


85-46 


4-20 


1-07 


0-29 


2-44 


1-34 


75-15 


4-93 


1.07 


2-85 


5-04 


1-31 


88-72 


4-50 


0-18 




3-24 • 


1-255 


82-25 


5-84 


1-11 


1-22 


3-58 


1-28 


78-36 


5-59 


1-86 


3-01 


5-58 


1-300 


77-87 


5-09 


•57 


2-73 


9.52 


1-301 


79-09 


5-20 


•66 


2-41 


8-34 


1-29 


73-84 


5-14 


1-47 


2-34 


8-29 


1-283 


7S-13 


;--53 


.54 


1-88 


8-02 


1-29 


77-98 


4-39 


0-57 


0-96 


8-55 


1-39 


74-70 


4-79 


1-2S 


0-91 


3-60 


1-32 


SO-70 


.'•66 


1-35 


2-39 


4-3S 


1-358 


85-52 


3-72 


Trace 


0-12 


4-55 



G. 

1-45 
1-50 
1-6S 
3-26 
1-25 
3-96 
6-94 
2-39 
3-26 
5-34 
9-41 

3-21 
2-04 
1-52 
7-04 

3-55 
3-24 
4-88 
3-85 
4-43 
304 
3-57 
2-64 
5-31 
6-54 

10-96 
3-36 
6-00 
6-60 
4-22 
4-30 
8-92 
5-90 
7-55 

14-72 



H. 

85-0 

77-5 

86-53 

84-3 

79-11 

88-10 

71-7 

82-25 

85-83 

86-54 

83-9 

74 98 

68-4 

92-9 



61-42 

85-5 

88-2:; 

65-2 
85-1 

82-0 

79-8 

67-1 

83-69 

62-5 

82-5 

68-8 

65-6 

55-4 

,5S-n 

56-0 

66-2 

62-50 

63-1 

64-S 

So-0 



S30 



MEAN COMl'OSITION OF VARIOUS COALS. 



Table II. {continued). 



Locality or Xame of Coal. 



NEWCASTLE. 

Williugton 

Andrews House, Tanfield 

Bowden Close 

Haswell "Wallsend 

Xewcastle Hartlej' 

liodley's Hartley 

Bates'" West Hartley 

West Hartley Main 

Buddie's West Hartley 

Hastings' Hartley 

Carr's Hartley 

Davison's West Hartley 

North Percy Hartley 

Haswell Coal Co.'s Steaui-boat 

Wallsend 

Derwentwater Hartley 

Broomhill 

Original Hartley 

Cowpen and Sidney's Hartley.... 

DERBYSHIRE. 

i^]arl Fitzwilliam's Elseear 

tloyland and Co.'s Elseear 

■;arl Fitzwilliam's Park Gate 

Butterly Co.'s Portland 

Butterly Co.'s Langley 

Stavely 

uoscoe Soft 



LANCASHIRE. 

ince Hall Co.'s Arley 

llaydock Little Delf. 

Balcarres Arley 



Blackley Huffit 

luce HallPemberton Yard 

Haydock Rushy Park 

Moss Hall Pem'berton Four-feet 

ilaydock Higher Florida 

Ince Hall Pemberton Four-feet. 
[51ackbrook Little Delf. 

King 

Rushy Park Mine 

Blackbrook Rushy Park 

.loliQSon & Wirthington's Rushy 

Park 

Laffak Rushy Park 

Balcarres Haigh Yard 

Hay dock Florida Main 

Wigan Four-feet 

Ince Hall Pemberton Five-feet... 

Oannel (Wigan) 

Ince Hall Co.'s Furnace Vein 

Balcarres Lindsay 

Caldwell and Thompson's Rushy 

Park -._ 

Balcarres Five-feet 

Moss Hall Pemberton Five-feet.. 

Moss Hall Co.'s New Mine 

Caldwell and Thompson's Higher 

Delf 

Johnson and Wirthington's Sir 

John 



11-26 

1-286 
'l-29 

ir3i 

1-25 

1-264: 

1-23 
1-25 
1-25 
1-25 
1-25 

1-27 
1-26 
1-25 
1-25 
1-26 



1-296 

1-317 

1-311 

1-301 

1-264 

1-2' 

1-285 



1-272 

1257 

1-26 

1-26 

1-34S 

1-3'. 

1-258 

1-218 

1-270 



B. 

S6S1 
85-58 
84-92 
83-47 
81-81 
80-26 
80-61 
81-85 
80-75 
82-24 
79-83 
83-26 
80-03 

83-71 
78-01 
81-70 
81-18 
82-20 



81-93 
80-05 
80-07 
80.41 
77-97 
79-85 
77-49 



82-61 
79-71 
83-54 
82-01 
80-78 
77-65 
75-53 
77-33 
77-01 



1-26 


82-70 


1-300 


73-66 


1-28 


77-76 


1-27 


81-16 


1-28 


79-50 


1-35 


80-47 


1-28 


82-26 


1-267 


77-49 


1-209 


78-86 


1-269 


68-72 


1-23 


79-23 


1-314 


74-74 


1-26 


83-90 


1-271 


76-17 


1-26 


74-21 


1-283 


76-16 


1-278 


77-50 


1-274 


75-40 


1-31 


72-86 



c. 

4-96 
5-31 
4-53 
6-68 
5-50 
5-28 
5-26 
5-29 
5-04 
5-42 
5-11 
5-31 
5-08 

5-30 
4-74 
6-17 
5-56 
5-10 



4-85 
4-93 
4.92 
4-65 
5-58 
4-84 
4-86 



5-86 
5-16 
5-24 
5-55 
6-23 
5-53 
4-82 
5-56 
3-93 
5-55 
5-30 
5-23 
5-99 

5-15 

5-72 
5-47 
5-50 
5-29 
4.76 
6-08 
5-71 
5-66 

5-46 
5-03 
5-35 
4-84 



D. 

1-05 
1-26 
0-96 
1-42 
1-28 
1-16 
1-52 
1-69 
1-46 
1-61 
1-17 
1-72 
0-98 

1-06 
1-84 
1-84 
0-72 



1-27 
1-24 
2-15 
1.58 
.80 
1-25 
1-64 



1-76 
-54 
•98 
1-6.S 
1-30 
2-50 
2-05 
1-01 
1-40 
1-48 
1-68 
1-32 
1-35 

1-21 
1-27 
1-25 
1-27 
•86 
2-20 
1-13 
1-58 
1-40 

1-09 

1-29 



1-41 

1-07 



E. 

0-88 
1.32 
0-65 
•06 
1-69 
1-78 
1-85 
1-13 
1-04 
1-35 
0-82 
1-38 
0-78 

1-21 
1-37 
2-85 
1-44 
0-71 



-91 
lC'6 
1-11 

-86 
114 
u-72 
1-30 



-80 
-52 
•05 
1-43 
1-S2 
1-73 
3-04 
1-03 
1-05 
1-07 
t-58 
1-01 
1-62 

2-71 

1-48 
•88 
1^19 
1.35 
1-43 
-96 
1-51 

•91 
2-09 
1-05 
1-36 

2-43 

1-54 



F. 

5-22 
4-39 
6-60 
8-17 
2-58 
2-40 
6-51 
7-53 
7-86 
6-44 
7-86 
2-50 
9-91 

2-79 
10-31 
4-37 
8-03 
7-97 



8-58 
8-99 
9-95 
11-26 
9-86 
lU-.)6 
12-41 



7-44 

10-65 

5-87 

5-28 

7-53 

10-91 

7-98 

12-02 

5-52 

4-89 

9-06 

8-99 

7-20 

9-24 
8-33 
5-64 

12-84 
9-57 

18-63 
7-24 

13-52 
5-53 

14-87 

8-69 

10-13 

12-16 

19-98 

8-15 



G. 

1-08 
2-14 
2-28 
0-20 
7-14 
9-12 
4-25 
2-51 
3-85 
2-94 
5-21 
5-84 
3-22 



2-46 
3-73 
1-80 
1-23 
4-65 
2-40 
2-30 



•L 

72-19 
65-13 
69-69 

04-61 
72.31 

59-20 

35-60 
60-63 
59-49 
57-18 

61-38 
54-83 
59-20 

58-22 
58-59 



61.6 

62-5 

61-7 

60-9 

54-9 

57-86 

5-2-8 



1-53 
3-42 
3-32 
4^05 
2-34 
3-68 
6-58 
3-05 
1-09 
4-31 
8-72 
1-69 
2-68 

2-19 
2-82 
3-90 
2-02 
4-23 
14-34 
4-84 
4-04 
2-00 

1-50 
9-21 
6-02 
3-16 

5-95 

11-40 



64-p 

Oftl 

62-89 

57-b4 

60-6 

59-4 

55-7 

51-1 

57-1 

58i48 

62-4 

56-66 

58-10 

57-52 

56-26 

66-09 

54-4 

60-0 

56-5 

60-33 

58-4 

57:84 

58-7 
55-90 
56-1 
57-7 

54-2 

56-15 



MEAN COMPOSITION OF VARIOUS COALS. 



331 



Table II, {continued) 



Locality or Name of Coal. 



SCOTCH. 

Wallsend Elgin 

Wellewood 

Dalkeith Coronation Seam. 
Kilmarnock Skerrington ... 

Fordel Splint 

Grangemouth 

Egliuton 

Dalkeith Jewel Seam 



IRISH. 

Slieverdagh Irish Anthracite., 



VARIOUS. 
Coleshill Co.'s Bagilt Main 

Ewloe 

Ibstock 



PATENT FUELS. 
JVarlich's Patent Fuel 

"Livingstone's Steam Fuel. 

Lyon's Patent Fuel 

Wvlam's 

Bell's 

Holland and Green's......... 



VAN DIEMAN'S LAND. 

South Cape 

Mount Nicholas Break o' Day. 

Tingal 

Jerusalem 

Douglas River, East Coast 

Tasman's Peninsula 

Schonten Island 

Whale's Head, South Cape 

Adventure Bay 



Sydney, New South Wale 



Borneo (Labuan kind) 

" Ihree-feet Seam... 
" Eleven-feet Seam., 



Formosa Island 

Vancouver's Island.. 
Lignite, Trinidad 

CHILI. 

Conception Bay 

Port Famine 

Chirique 

Laredo Bay 

Talcahnano Bay 

Colcurra Bay 



PATAGONIA. 

Sandy Bay, No. 1 , 

No. 2 



A. 

1-20 
1-27 
1-31G 

1-24:1 

1-2.3 
1-29 
1-25 
1-277 



1-269 
1-275 
1-291 



1-15 

1-184 

1-13 

1-10 

1-11 

1-302 



1-28 
1-37 
1-21 



B. 

76-09 
81-.36 
76-9i 
79-82 
79-58 
79-85 
80-08 
74-55 



88-48 
80-97 
74-97 



86-07 
86-36 
79-91 
87-88 
70-14 



63-40 
57-37 
57-21 
68-18 
70-44 
65-54 
64-01 
65-86 
80-22 

8-2-39 

64-52 
54-31 
70-33 

78.26 
66-93 
65-20 



70-55 
64-18 
38-98 
58-67 
70-71 
78-30 



62-25 
59-63 



C. 

5.22 
6-28 
5-20 
5-S2 
5-50 
5-28 
6-50 
5-14 



2-30 



5-62 
4-96 
4-83 



5-56 

4-13 

4-56 
5-69 
5-22 
4-65 



2-89 
3-91 
3-38 
3-99 
4-20 
3-36 
3-55 
3-18 
3-05 

5-32 

4-74 
5-03 
5-41 

5-70 
5-32 
4-25 



5-76 
5-33 
4-01 
5-52 
6-44 
5-50 



5.05 
5-68 



D. 

1-41 
1-53 
Trace. 

•94 
1-13 
1-35 
1-55 
0-10 



0-23 



2-02 
1-10 



Trace. 

1-80 
1-06 
1-68 
0-81 
1-15 



1-27 
1-15 
1-20 
1-62 
1-11 
1-91 
0-94 
1-12 
1-36 

1-23 

0-80 
0-98 
0^67 

0-64 
1-02 
1-33 



0-95 
0-50 

0-58 
0-71 
l-'-8 
10,) 



0-63 
0-64 



E. 

1-53 

1-57 
0-38 
•86 
1-46 
1-42 
1-38 
0-33 



6-76 



1-36 
1-40 
1-45 



1-62 

1-45 
1-29 
1-25 
0-71 



0-98 
0-90 
1-32 
1-12 
0-70 
1-03 
0-85 
1-14 
1-90 

0-70 

1-45 
1-14 
1-17 

0-49 
2-20 
0-69 



1-98 
1-03 
6-T4 

i-i; 

0-it4 
lOo 



1-13 
0-96 



F. 

5-05 

6-37 

14-37 

11-31 

8-33 

8-58 

8-05 

15-51 



Included 
in Ash. 

0-86 

8-20 

11-88 



Included 
in Ash. 

2-03 

• 2-07 

6^63 

0^42 



1^01 
9-10 

7-80 
5-89 
9-27 
1-75 
3-38 
7-20 
4-SO 

8-32 

20-75 
24-22 
19-19 

10-95 

8-70 
21-69 



L3-24 

13-38 

17-:'3 

13-9.S 

b-o7 



17-54 
17-45 



U. 
10-70 
2-89 
310 
1-25 
4-00 
3-52 
2-44 
4-37 



10-80 



1-62 
3-37 
5-99 



2-91 

4-52 
4-66 
4-84 
4-96 
13-73 



30-45 
27-55 
29-09 
19-20 

14-3.S 
26-41 
27-17 
21-50 
S-67 

2-0 i 

7-74 

14-32 

3-23 

3-9 ■ 

15-S^ 
6-8 i 



6-.U 

;;6-,)i 

1 <V6'^ 
iryi 
5-68 



13-40 
15-64 



H. 

58-4.J 

59-15 

53-5 

49-3 

5-i-03 

56-6 

5;-9; 

49-S 



55-8 
54-5 
50-8 



85-1 



65-8 
71-7 






MEAX COMPOSITION OF YAEIOUS COALS. 



Table III. Average Value of Coals from different LocaliLiis. 



Average of 37 samples from Wales 
" 17 " Newcastle.. 

" 2S " Lancashire. 

" 8 " Scotland 

" 8 " . Derbyshire 



^"S 


•^t^— ■ 


IIS 




o%'^. 












^■^s 


SP'«o 












?^l 


s 


A. 


9-05 


8-37 


7-9-4: 


7-70 


7-58 



t, . 


■g 




(O 


£ 2 


.H§ 


gft 




c"? 


I-l* 


o a 


11 

;2S 






> ^ 


£=* 






O-^ 


-S^ 


^•o 


|o 


p^ 


Is 


B. 


c. 


4i8-2 


53-1 


411-1 


-;9-S 


447-6 


49-7 


431-4 


. 0-0 


432-7 


^7-2 











a 


g ^^ 






r-l 


a*^* 


-i 




"B.H 


5-9 S 
















t = a 


§ 














3J 

1 


D. 


£. 


42.71 


60-9 


45-3 


67-5 


4.3-15 


73-5 


49-y9 


73-4 


47-45 


80-9 



Tabi^k IY. Average Composition of Coals from different Localities 



Locality. 




c 


i 


1 


3 
-a 
1 


O 


■i 
< 


i 


Average of 36 samples from Wales 


A 

1-315 
1-256 
1-273 
1-259 
1-292 


B. 

8.3-78 
82-12 
77-90 
78-53 
79-68 


C. 

4-79 

5-31 

5-32 

5-61 

4-94 


D. 

0-98 
1-35 
1-30 
1-00 
1-41 


E. 

1-43 
1-24 
1-44 
1-11 
1-01 


F. 

4-15 
5-69 
9-53 
9-69 
10-28 


G. 

4-91 

3-77 

4-88 

4-03 

2-65 


H. 

72.60 
60-67 
60-22 
54-22 
59-32 


" 28 " Lancashire 

" 8 " Scotland 


j " 7 " Derbyshire 

1 



APPENDIX. 



USEFUL RULES IN MENSURATION, 

354. To find the Circumference of a Circle the Diameter 

being given, and vice versa. 

1. Multiply the diameter by 3 '1416, and the result will be 
the circumference. 

2. Divide the circumference by 3 '1416, and the result will 
be the diameter. 

355. To find the Area of a Circle, having given the Diameter, 

and vice versa. 

1. Multiply the square of the diameter by •t854, and the 
result will be the area. 

2. Divide the area by '7854, and take the square root of the 
quotient, which will give the diameter. 

356. To find the Surf ace of a Cylinder, having given the 
Diameter and Length. 

Multiply the diameter by 3*1416 to get the circumference of 
the section, and again multiply this product by the length of 
the cylinder. 

35 T. To find the Volume of a Cylinder, having given the 
Diameter and Length, 

Multiply the square of the diameter by -7854 to get the 
a-rea of the section, and then multiply this area by the length. 

358. To find the Surface of a Sphere. 

Multiply the diameter of the sphere by its circumference, 
and the product will be the surface. 

359. To find the Volume of a Sphere. 

Multiply the cube of the diameter by '5236, and the product 
will be the volume required. , 

333 



834 



EULES ly MEXSUKATION. 



360. To find the Volume of a Gone. 
Proceed exactly as in art. 35*7, and divide the result by 3, 

361. Circular Inch ; Comparison of Circular Inch and 
Square Inch. 

A circular inch is a circle whose diameter is an inch ; and 
consequently its area is less than a square inch, being the circle 
inscribed within the square inch. Since the area of a circle is 
found by multiplying the square of its diameter by ■'7854, there- 
fore the area of a circular inch ="*7854Xl^=''7854 ; and hence 
the number of square inches in any surface being given, divide 
that number by '7854, and the result will be the number of 
circular inches ; and, on the contrary, the number of circular 
inches in any surface being given, multiply by "7854, and the 
result will be the number of square inches. 

362. To find the Area of an Ellipse. 

Multiply the greatest and least diameters together, and that 
product by -7854, and the result will be the area. 

363. To find the Circumference of an Ellipse. 

Multiply half the sum of the two diameters by 3-1416, 
and the result will give the circumference sufficiently accu- 
rate for practice. 

364. Definition. 

The frustrum of a cone is the part that is left after the top 
or end is cut off by a plane parallel to the base. 

365. To find the Volume of the Frustum of a Cone. 

Multiply the areas of the two ends together ; to the square 
root thereof add the two areas ; that sum multiplied by one- 
third the height gives the solid content. 

366. To find the Weight of a known Substance of given 
Dimensions. 

Having found the volume, if the result be in cubic feet, 
multiply the weight of a cubic foot, as given in Table Gr, 



ON SELECTING COAL. 



33o 



p. 355 ; but if the volume be in cubic inches, divide the 
product so obtained by It 28. 

36t. Useful Rules to he observed when Coaling. 

1. Before purchasing coal, it is advisable to inspect the 
"bill of lading," which, by giving the name or locality of the 
mine, will enable the officer to ascertain its quality by refer- 
ence to the Tables given in the miscellaneous Chapter ; it will 
also give the quantity of the coal, and may rectify mistakes of 
false weighing when purchasing coals on foreign stations. 

2. If there be a choice of fuel, care should be taken, gener- 
ally speaking, to select the best ; for although dearer at first, 
it will be found most economical in the end. It is a common 
occurrence for a steam-vessel to consume 30 or 40 per cent, 
more coal when of an inferior quality than she would other- 
wise do ; while the price per ton is not more than two or 
three shillings cheaper than that of a better kind. In addition 
to which, the speed of the ship will probably not be so great ; 
while the labor of the stokers will be increased. 

3. The coals selected should be dry, and the officer should 
satisfy himself that they have not been exposed for any length 
of time in the open air to the influence of the sun's rays, 
especially in a tropical climate ; for under such circumstances 
coals rapidly deteriorate from a species of slow combustion 
(p. 33*7). In case, as may sometimes happen, no other coals 
can be procured, he should take especial care not to receive 
those which have formed the exposed surface. 

4. Coal having a brassy appearance, thus indicating the 
presence of iron pyrites, should be avoided ; or, if received, it 
should be borne in mind that such coal has a tendency to 
spontaneous combustion, which is much increased by wet or 
moisture : and it should be remembered that wet coals have a 
very injurious effect on the coal-bunkers, especially when 
wetted with salt-water (p. 324). 

22 



3^ 



PKESSUKE, TEMPERATURE, ETC. 



TABLE A. 

Pressures of Steam, and the corresponding Temperatures 
and relative Volumes. 



it 

ii 
11 


1 


6 
-o 

> 


p. 
.S.S 

i'l 




. 05 

a 

"o 

> 
® 

1 


I 
a a 


il 

P 


1 


1 


103-0 


20911 


25 


240-9 


1043 


49 


281-4 


564 


2 


126-0 


10890 


26 


243-2 


1006 


50 


282-7 


554 


3 


141-0 


7446 


27 


245-3 


972 


51 


284-0 


543 


4 


152-2 


5690 


28 


247-4 


939 


52 


285-2 


533 


5 


161-4 


4620 


29 


249-4 


910 


53 


286-4 


525 


6 


169-2 


3899 


30 


251-4 


882 


54 


287-6 


516 


t 


175-9 


3378 


31 


253-3 


856 


55 


288-8 


507 


8 


182-0 


2984 


32 


255-2 


832 


56 


290-0 


499 


9 


187-4 


2675 


33 


2571 


809 


57 


291-2 


492 


10 


192-4 


2426 


34 


258-9 


787 


58 


292-4 


484 


11 


197-0 


2222 


35 


260-6 


766 


59 


293-6 


476 


12 


201-3 


2050 


36 


262-3 


747 


60 


294-8 


468 


13 


205-3 


1903 


37 


264-0 


- 728 


61 


295-9 


462 


14 


209-0 


1777 


38 


265-6 


711 


62 


297-0 


455 


15 


212-9 


1669 


39 


267-2 


694 


63 


298-1 


448 


16 


216-3 


1573 


40 


268-8 


678 


64 


299-2 


442 


U 


219-6 


1488 


41 


270-2 


663 


65 


300-2 


436 


18 


222-7 


1411 


42 


271-7 


649 


66 


301-2 


430 


19 


225-6 


1343 


43 


273-2 


635 


67 


302-3 


424 


20 


228-4 


1281 


44 


274-6 


622 


68 


303-3 


418 


21 


231-1 


1225 


45 


276-0 


609 


69 


304-3 


413 


22 


233-8 


1173 


46 


277-4 


597 


70 


305-3 


407 


23 


,236-3 


1126 


47 


278-8 


585 








24 


238-6 


1083 


48 


280-1 


574 









TEMPERATURES. 8S7 



TABLE B. 

General Effects of Heat according to certain Temperatures, 

Fahrenheit. 

Extremity of Wedgwood's scale 32211^ 

Cast iron thoroughly melted 205 Yt 

Cast iron begins to melt.. lt9Tt 

Welding heat of iron (greatest) 1342T 

(least) 127n 

Fine gold melts 523t 

Fine silver melts ,. 4Ht 

Swedish copper melts 458t 

Brass melts 380t 

Red'heat fully visible in daylight lOtt 

Iron red-hot in twilight 884 

Heat of a common fire "TOO 

Iron bright red in the dark Y52 

Zinc melts TOO 

Quicksilver boils 660 

Linseed-oil boils 600 

Lead melts 594 

Polished steel acquires a deep-blue color 580 

Oil of turpentine boils.,..,,,. 560 

Bismuth melts 416 

Polished steel acquires a pale straw-color 460 

Tin melts 442 

Tin and bismuth (equal parts) melt 283 

Sulphur melts 226 

A saturated solution of salt boils 218 

Water boils 212 ' 

Five parts bismuth, three of tin, and two 

of lead melt ; 212 

Eight of bismuth, three of tin, and five of 

lead melt 210 

Alcohol boils 174 

Beeswax melts 142 

Spermaceti melts , 112 



338 EXPANSION BY HEAT. 

Fahrenheit 

Vital heat 96° 

Tallow melts ^.... 92 

Olive-oil begins to solidify 36 

Fresh water freezes 32 

Sea-water freezes 28 

Strong wines freeze .' 20 

Oil of turpentine solidifies 14 

Alcohol one part, water three parts t 

Proof spirits # 

Alcohol one part, water one part — t 

Freezing-point of quicksilver — 39 

Alcohol becomes oily — 132 



TABLE C. 

Of the linear Expansion of Solid Bodies hy Heat. 

Dimensions which a bar takes at 212° whose length at 32° is I'OOOOOO. 



Cast iron 100111111 

Steel (rod) l-001144t0 

Steel, not tempered l-OOlOYSrS 
Ditto, tempered 

yellow 1-00136900 

Ditto, at a higher 

rate 1-00123956 

Iron 100118203 

Soft iron, forged... 1-00122045 

Gold 1-00150000 

Copper 1-00191000 



Cast brass 1-0018150 

Silver 1-0018900 

Tin 1-0028400 

Lead 1-00284836 

Zinc 1-00294200 

Glass from 32° to 

212°... 1-00086130 

Glass from 212° to 

392° 1-00091827 

Glass from 392° to 

572° .....1-00101114 



Expansion of Fluids hy Heat. 

Mercury from 32° to 212° 0-018099 

Ditto 212°to392o 0018184 

Ditto . 392° to 572° 0-018870 

Water from 39° to 212° 0-043320 

Alcohol (to its boiling-point) 0-1100 

Fixed oils 0-0800 



EXPANSION TABLE. 



3S9 



TABLE D. 



To 
keep the 
satura- 
tion at 


Ratio of feed and 

quantity blown out to 

the evaporation. 


BoUing- 

point in air 

at that 

degree of 
saturation. 


Boiling- 
point in a 

boiler 
loaded to 

10 lbs. 


Loss of 
Fuel per 
cent., the 
feed being 
supplied at 
100° F. 


Evapora- 
tion. 


Blown 
out. 


Feed. 




1 

1 
1 
1 


1 

I 
i 
i 


2 

1 
1 


214-4 
215-5 
216-6 
21t-9 


242-4 
243-5 
244-6 
245-9 


11-35 
6-06 
4-15 
318 



TABLE E. 



Portion of 
stroke 




Logarithm 


Portion of 
stroke 




Logarithm 


performed 
before 


Logarithm 


-^.+ 


performed 
before 


Logarithm 
^ I 


«^i+ 


expansion, 

I' 


• ''r+c 


- .^ 


expansion, 
I' 


^'vTc 


l+c 


-10 


0-823930 


0-411139 


-25 


0-522835 


0-319106 


-11 


0-t95880 


0-409164 


-26 


0-508664 


0-313656 


•12 


0-^69525 


0-402433 


-21 


0-494850 


0-301924 


•13 


0-U4t62 


0-395326 


-28 


0-481443 


0-302331 


•14 


0-121233 


0-388456 


-29 


0-461495 


0-296665 


-15 


0-698910 


0-381656 


-30 


0-455910 


0-291141 


•16 


0-611189 


0-314932 


•31 


0-443132 


0-285182 


-11 


0-651629 


0-368413 


•32 


0-431846 


0-280518 


•18 


0-638289 


0.361911 


-33 


0-420286 


0-215081 


•19 


0-619823 


0-355643 


-34 


0-408918 


0-269980 


•20 


0-602060 


0-349211 


-35 


0-391940 


0-264818 


•21 


0-585009 


0-343014 


-36 


0-381212 


0-259594 


•22 


0-568611 


0-331060 


31 


0-316159 


0-254548 


•23 


0-552190 


0-330819 


-38 


0-366610 


0-249443 


-24 


0.531561 


0-325105 


-39 


0-356599 


0-244211 



340 



EXPANSION TABLE. 



Portion of 
stroke 

performed 
before 

expansion, 
V 


Logarithm 


Logarithm 


Portion of 
stroke 

performed 
before 

expansion, 

o4 


Logasithm 


Logarithm 


•40 


0-346U4 


0-239550 


•65 


0-155032 


0-125156 


•41 


0^33Y259 


0-234517 


•66 


0^148911 


0-120903 


•42 


0-3279Y2 


0-229682 


•67 


0142702 


0-116608 


•43 


0^318689 


0-224792 


-68 


0136721 


0-112270 


•44 


0-309843 


0-220108 


•69 


0-130655 


0-107888 


•45 


0-301030 


0-215373 


-70 


0-124820 


0^103462 


•46 


0-2924^8 


0-210586 


■71 


0-119256 


0-099335 


•4t 


0-283979 


0-205745 


•72 


0-113609 


0-093422 


•48 


0-2'75tt2 


0-201124 


•73 


0-107888 


0-090963 


•49 


0-261641 


0-196452 


•74 


0-102434 


0-086716 


•50 


0^259594 


0191730 


•75 


0-096910 


0-082785 


•51 


0-251881 


0-187239 


•76 


0-091667 


0-078094 


•52 


0-2442n 


0-182700 


•77 


0-086360 


0-074085 


•53 


0-236537 


0-178113 


•78 


0-080987 


0-070030 


•54 


0.2291T0 


0-173478 


•79 


0-075912 


0-065953 


•55 


0-221936 


0-169086 


-80 


0-070776 


0-061452 


•56 


0-214579 


0-164650 


-81 


0-065580 


0-057286 


•5T 


0-207634 


0-159868 


•82 


0-060320 


0-053463 


•58 


0-200577 


0-155640 


•83 


0-055378 


0-048830 


•59 


0-193959 


0-151370 


•84 


0-050380 


0-044931 


•60 


0-187239 


0-146748 


•85 


0-045714 


0-040998 


•61 


0-180413 


0-142389 


•86 


0-040998 


0-036629 


•62 


0-174060 


0-137987 


•87 


0-036229 


0-032619 


•63 


0-167613 


0-133858 


•88 


0-031408 


0-028164 


•64 


0-161068 


0-129368 


•89 


0-026942 


0-024075 








•90 


0-022428 


0-019947 



CAPACITIES FOE HEAT. 



341 



TABLE F. 

Of Caj^acities of Bodies for Heat referred to Water as 
the Standard. 



Water 

Ice 

Olive-oil 

Alcohol A... 

Linseed-oil 

Oil of turpentine.... 

Pit-coal 

Chalk 

Sea-salt 

Sulphur 

Ashes of cinders.... 

Black-lead 

Ashes of elm-wood. 
Iron 



0000 
9000 

noo 

TOOO 

5280 
4720 

27n 

2100 
2300 
1900 
1855 
1830 
1402 
1300 



Hardened steel ..: 

Steel softened by fire. 

Soft bar-iron 

Brass 

Copper 

Zinc 

Ashes of charcoal 

Sih^er 

Tin 

White-lead 

Gold 

Lead 

Mercury 



•1230 
•1200 
•1190 
•1160 
•1140 
•1000 
•0909 
•0820 
•0Y04 
•06T0 
•0500 
•0420 
•0330 



TABLE G. 

Mechanical Properties of Materials. 



Names of materials. 



Air (atmospheric). 
Ash :... 



Beech 



Birch (common) .... 
iDitto (American)... 
Bismuth (cast) ...... 

iBox (dry) 

Brass (cast) 

Ditto (wire-drawn) 



Specific 
gravity. 



•001228 

•690 to 

•845 

•854 to 

•690 

•192 

•648 

1-810 

•960 

;-399 

1-544 



Weight of 

1 cubic foot 

in lbs. 



0-0168 

43-12 to 

53-81 

53-3Yto 

43-12 

49-50 

40-50 
613-81 

60-00 
525-00 
534-00 



Tenacity 
per square 
inch in lbs. 



lT20t 
15t84 to 
11850 
15000 

3250 
19891 

11968 



342 MECHANICAL PROPERTIES OF VARIOUS BODIES. 



Names of materials. 



Specific 
gravity. 



Weight of 

1 cubic foot 

in lbs. 



Tenacity 
pel" square 
inch in lbs. 



Cedar (Canadian, fresh)... 

Ditto (seasoned) 

Chalk 

Chestnut 

Clay (common) 

Coal (Welsh furnace) 

Ditto (Coke) 

Ditto (Alfreton) 

Ditto (Butterly) 

Ditto (Coke) 

Ditto (Welsh stone) 

Ditto (Coke) 

Ditto (Welsh Slaty) 

Ditto (Derbyshire Cannel) 

Ditto (Kilkenny) 

Ditto (Coke) 

Ditto (Slaty) 

Ditto (Bonlavoomeen) .... 

Ditto (Coke) 

Ditto (Corgee) 

Ditto (Coke) 

Ditto (Staffordshire) 

Ditto (Swansea) 

Ditto (Wigan) 

Ditto (Glasgow) 

D itto (Newcastle) 

Ditto (common Cannel)... 

Ditto (slaty Cannel) 

Copper (cast) 

Ditto (sheet) 

Ditto (wire-drawn) 

Ditto (in bolts) 

Deal (Christiana middle) . 

Ditto (Memel middle) 

Ditto (Norway Spruce)... 

Ditto (English) 

Elm (seasoned) 

Fir (New England) ........ 

Ditto (Riga) 



0-909 

0-Y53 

2-184 to 

1-869 

0-65t 

1-919 

l-33t 

1000 

1-235 

1-264 

1-000 

1-368 



-390 

■409 

-278 

-602 

-65t 

•443 

-436 

1-596 

1-403 

1-656 

1-240 

l-35t 

1-268 

1-290 

1-257 

1-232 

1-426 

8-601 

8-785 

8-878 

0-698 
0-590 
0-340 
0-470 
0-588 
0-553 
0-753 



56-81 

47-06 
174-00 to 
116-81 

41-06 
119-93 

83-66 

62-50 

77-18 

79-00 

68-75 

85-50 

86-87 

88-06 

79-87 
100-12 
103-56 

90-18 

89-75 

99-75 

87-68 
103-50 

78-12 

84-81 

79-25 

80-62 

78-56 

77-00 

8^-12 
537-93 
549-06 
560-00 



11400 



43-62 
36-87 
21-25 
29-37 
36-75 
34-56 
47-06 



19072 

61228 
48000 
12400 

17600 

7000 

13489 

11549 to 
12857 



MECHANICAL PROPERTIES OF VARIOUS BODIES. 343 



Names of materials. 



Iron (wrought English) 

Dittb (in bars) 

Ditto (hammered) 

Ditto Russian (in bars) 

Ditto Swedish (in bars) 

Ditto English (in wire, J^ 

inch in diameter) 

Ditto Russian (in wire, ^V to 

3^0 inch in diameter) 

Ditto (rolled in sheets, and 

cut lengthwise) 

Ditto (cut crosswise) 

Ditto (in chains, oval links, 6 

inch clear,iron^in. diameter) 

Ditto (Brunton, with stay 

across links) 

Ditto, cast (Carron, No. 2, 

cold blast) 

Ditto (hot blast) 

Ditto, cast (Carron, No. 3, 

cold blast) 

Ditto (hot blast) 

Ditto (Devon, No. 3, cold 

blast) 

Ditto (hot blast) 

Ditto (Buffery, No. 1, cold 

blast) 

Ditto (hot blast) 

Ditto (Coed Talon, No. 2, 

cold blast) 

Ditto (hot blast).. 

Ditto (Coed Talon, No. 3, 

cold blast) 

Ditto (hot blast) 

Ditto (Elsicar, No. 1, cold 

blast) 

Ditto (Milton,No.l,hot blast) 
Ditto (Muirkirk, No. 1, cold 

blast) 

Ditto (hot blast) 



Specific 
gravity. 



t-TOO 
7 -600 to 
7-800 



7-066 
•7-046 



094 
056 

295 
229 



1-019 
6-998 

6-955 
6-968 

Y-194 
6-910 

7-030 
6-976 



7-113 
6-953 



Weight of 

1 cubic foot 

in lbs. 



481-20 

475-50 
487-00 



441-62 
440-37 

443-37 
44100 

455-93 
451-81 

442-43 
437-37 

434-06 
435-50 

449-62 
435-62 

439-37 
436-00 

444-56 
434-56 



Tenacity 
per square 
inch in lbs. 



15Jtons. 



251 tons. 
30 tons. 
27 tons. 
32 tons. 

36 to 43 

fons. 
60 to 91 

tons. 
14 tons. 
18 tons. 

211 tons. 

25 tons. 

16683 
13505 

14200 
17755 



21907 

17466 
13434 

18855 
16676 



844 MECHANICAL PROPERTIES OF VARIOUS BODIES. 



Names of materials. 



Lead (cast English) 

Ditto (milled sheet) 

Ditto (wire) 

Lignum Yitae 

Mahogany (Spanish) 

Mercury at 32° 

Ditto at 60° 

Oak (English) 

Ditto (Canadian) 

Ditto (Dantzic) 

Ditto (Adriatic) 

Ditto (African middle) .... 

Pine (pitch) 

Ditto (red)..... 

Ditto (American yellow) . 

Silver (Standard) 

Slate (Welsh) 

Steel (soft) 

Ditto (razor tempered) ... 

Teak (dry) 

Tin (cast) 

Water (sea) 

Ditto (rain) '. 

Walnut 

Zinc 



Specific 


gravity. 

1 1 


11-446 


11 


A01 


11 


31Y 


1 


220 





800 


13 


619 


13 


580 





934 





S12 





t56 





993 





•972 





660 





•65T 





•461 


10 


312 


2 


888 


1 


Y80 


1 


840 





65Y 


1 


291 


1 


02t 


1 


000 





6tl 


1 


•028 



Weight of 

1 cubic foot 

in lbs. 



nt-45 

112-93 

105-12 

16-25 

50-00 

851-18 

848-15 

58-31 

54-50 

41-24 

62-06 

60-15 

41-25 

4106 

28-81 

644-50 

180-50 

486-25 

490-00 

41-06 

455-68 

64-18 

62-50 

41-93 

439-25 



Tenacity 
per square 
inch in lbs. 



18^24 

3328 

2581 

11800 

16500 



11300 
10253 
12180 



1818 



40902 

12800 

120000 

150000 

15000 

5322 



8130 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



345 



TABLE H. 

Circumferences and Areas of Circles of given Diameters. 



DIAM. 


CIRCUM. 


AEEA. 


DIAM. 


CIRCUM. 


AREA. 








5 in. 


15-7080 


19-6350 


^ 


•3927 


•0122 


i. 


16-1007 


20-6290 


i 


•7854 


•0490 


1 


16-4934 


21-6475 


1 


1-1781 


•1104 


' 8 


16-8861 


22-6907 


2" 


1-5748 


•1963 


l. 


17-2788 


23-7583 


1 


1-9635 


•3068 


1 


17-6715 


24-8505 




2-3562 


•4417 




18-0642 


25-9672 


1 


2-7489 


•6013 


1 


18-4569 


27-1085 


lin. 


3-1416 


•7854 


6 in. 


18-8496 


28-2743 


i 


3-5343 


•9940 


i 


19-2423 


29-4647 


X 
4 


3-9270 


. 1-2272 


i 


19-6350 


30-6796 




4-3197 


1-4848 


f 


20-0277 


31-9192 


i 


4-7124 


1-7671 




20-4204 


33-1831 


•1 


5-1051 


2-0739 


1 


20-8131 


34-4717 


f 


5-4978 


2-4053 


1 


21-2058 


35-7847 


I 


5-8905 


2-7611 


i 


21-5985 


37-1224 


2 in. 


6-2832 


3-1416 


7 in. 


21-9911 


38-4846 


i 


6-6759 


3 5465 


\ 


22-3838 


39-8713 


i 


7-0686 


3-9761 




22-7765 


41-2825 




7-4613 


4-4302 


1 


23-1692 


42-7184 


1 


7-8540 


4-9087 


J. 


23-5619 


44-1786 


1 


8-2467 


5-4119 


1 


23-9546 


45-6636 


f 


8-6394 


5-9396 


f 


24-3473 


47-1730 


i 


9-0321 


6-4918 


1 


24-7400 


48-7070 


Sin. 


9-4248 


7-0686 


8 in. 


25-1327 


50-2655 


i 


9-8175 


7-6699 


^ 


' 25-5254 


51-8486 




10-2102 • 


8-2957 


i 


25-9181 


53-4562 


1 


10-6029 


8-9462 


1 


26-3108 


55-0885 


^ 


10-9956 


9-6211 




26-7035 


56-7450 


1 


11-3883 


10-3206 


1 


27-0962 


58-4263 


3. 


11-7810 


11-0447 


a. 


27-4889 


60-1320 


f 


121737 


11-7932 


1 


27-8816 


61-8624 


4 in. 


12-5664 


12-5664 


9 in. 


28-2743 


63-6173 


\ 


12-9591 


13-3640 


i 


28-6670 


65-3967 




13-3518 


14-1863 


\ 


29-0597 


67-2006 1 


1 


13-7445 


15-0331 


f 


29-4524 


. 69-0292 


^ 


14-1372 


15-9043 


i 


29-8451 


70-8822 


1 


14-5299 


16-8001 


1 


30-2378 


72-7598 


\ 


14-9226 


17-7205 


f 


30-6305 


74-6619 


1 


15-3153 


18-6655 


i 


31-0232 


76-5886 



346 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



DTAM. 


CIRCUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


10 in. 


31-4159 


78-5398 


16 in. 


50-2655 


201-0619 


i 


31-8086 


80-5156 


i 


60-6582 


204-2168 


1 

4 


32-2013 


82-5159 


2. 


51-0509 


207-3942 


1 


32-5940 


84-5407 


1 


51-4436 


210-5971 


i 


32-9867 


86-5901 


i 


51-8363 


213-8246 


1 


33-3794 


88-6642 


1 


52-2290 


217-0767 


f 


33-7721 


90-7626 


1 


52-6217 


220-3533 


1 


34-1648 


92-8858 


1 


53-0144 


223-6544 


11 in. 


34-5575 


95-0332 


17 in. 


53-4071 


226-9801 


^ 


34-9502 


97-2054 


i 


53-7998 


230-3303 


1 


35-3429 


99-4020 


i 


54-1925 


233-7050 


1 


35-7356 


101-6238 


f 


54-5852 


237-1044 


i. 


36-1283 


103-8689 


i 


54-9779 


240-5282 


1 


36-5210 


106-1392 


1 


55-3706 


243-9766 


1 


36-9137 


108-4.340 


f 


55-7633 


247-4495 


i 


37-3064 


110-7534 


1 


56-1560 


250-9470 


12 in. 


37-6991 


113-0973 


18 in. 


56-5487 


254-4690 


i 


38-0918 


115-4658 


i 


56-9414 


258-0156 


i 


38-4845 


117-8589 


-. 


57-3341 


261-5867 


f 


38-8772 


120-2764 


V 


57-7268 


265-1824 




39-2699 


122-7185 


i 


58-1195 


268-8025 


1 


39-6626 


125-1852 


1 


58-5122 


272-3473 


1 


40-0553 


127-6763 




58-9049 


276-1165 


1 


40-4480 


130-1921 


1 


59-2976 


279-8104 


13 in. 


40-8407 


132-7323 


19 in. 


59-6903 


283-5287 


i 


41-2334 


135-2972 


i 


60-0830 


287-2717 


1 


41-6261 


137-8865 


1 

4 


60-4757 


291-0391 




42-0188 


140-5005 


1 


60-8684 


294-8305 


i. 


42-4115 


143-1388 




61-2611 


298-6477 


1 


42-8042 


145-8018 


1 


61-6538 


302-4888 


f 


43-1969 


148-4893 


1 


62-0465 


306-3544 


1 


43-5896 


151-2014 


¥ 


62-4392 


310-2446 


14 in. 


43-9823 


153-9380 


20 in. 


62-8319 ■ 


314-1593 


^ 


44-3750 


156-6992 


i 


63-2246 


318-0985 


1 


44-7677 


159-4849 


i 


66-6173 


322-0623 


f 


45-1604 


162-2953 


1 


64-0100 


326-0507 


i 


45-5531 


165-1299 




64-4026 


330-0636 


1 


45-9458 


167-9893 


1 


64-7953 


334-1011 




46-3385 


170-8732 


1 


65-1880 


338-1630 


1 


46-7312 


173-7817 


i 


65-5807 


342-2496 


15 in. 


47-1239 


176-7146 


21 in. 


65-9734 


346-3606 


i 


47-5166 


179-6722 


i 


66-3661 


350-4962 


1 

4 


47-9093 


182-6542 


1 

4 


66-7588 


354-6564 


f 


48-3020 


185-6609 




67-1515 


358-8412 


i 


48-6947 


188-6919 


^ 


67-5442 


363-0503 


1 


49-0874 


191-7477 


1 


67-9369 


367-2842 


■ f 


49-4801 


194-8278 


f 


68-3296 


371-5424 


1 


49-8728 


197-9326 


8 


68-7223 


375-8253 



CIRCUMFERENCES AND AREAS OF CIRCLES. S47 



DIAM. 


CIKCUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


22 in. 


69-1150 


380-1327 


' 28 in. 


87-9646 


615-7522 


X 


69-5077 


384-4646 


J. 


88-3573 


621-2623 


i 


69-9004 


388-8212 


1 


88-7500 


626-7968 


3 


70-2931 


393-2023 


1 


89-1427 


632-3561 


1 


70-6858 


397-6078 


i. 


89-5354 


637-9397 


1 


71-0785 


402-0379 


'l 


89-9281 


643-5480 


f 


71-4712 


406-4926 


f 


90-3208 


649-1807 


i 


71-8639 


410-9719 


7 
8 


90-7135 


654-8381 


23 in. 


72-2566 


415-4756 


29 in. 


91-1062 


660-5199 


i 


72-6493 


420-0039 


i 


91-4989 


666-2264 


1 


73-0420 


424-5568 


1 

4 


91-8916 


671-9572 




73-4347 


429-1343 




92-2843 


677-7128 


i 


73-8274 


433-7361 


i- 


92-6770 


683-4928 


1 


74-2201 


438-3626 


1 


93-0697 


689-2974 


1 


74-6128 


443-0137 


f 


93-4624 


695-1265 


i 


75-0055 


447-6892 


1 


93-8551 


700-9802 


24 in. 


75-3982 


452-3893 


30 in. 


94-2478 


706-8583 


1 


75-7909 


457-1140 


i 


94-6405 


712-7611 


1 

4 


76-1836 


461-8632 


i 


95-0332 


718-6884 




76-5763 


466-6370 




95-4259 


724-6403 


1 


76-9690 


471-4352 


1 


95-8186 


730-6167 


1 ' 


77-3617 


476-2581 


1 


96-2113 


736-6176 


f 


77-7544 


481-1055 


f 


96-6040 


742-6430 


1 


78-1471 


485-9775 


i 


96-9967 


748-6932 


25 in. 


78-5398 


490-8739 


31 in. 


97-3894 


754-7676 


1 


78-9325 


495-7949 


^ 


97.7821 


760-8668 


1 


79-3252 


500-7404 


A 


98-1748 


766-9904 


1 


79-7179 


505-7106 


1 


98.5675 


773-1387 


80-xie3 


510-7052 


i 


98-9602 


779-3113 


1 


80-5033 


515-7244 


1 


99-3529 


785-5086 


1 


80-8960 


520-7681 




99-7456 


791-7304 


i 


81-2887 


525-8364 


1 


100-1383 


797-9768 


■ 26 in. 


81-6814 


530-9292 


32 in. 


100.5310 


804-2477 


^ 


82-0741 


536-0465 


i 


100-9237 


810-5432 


± 


82-4668 


541-1884 


i 


101-3164 


816-8632 


1 


82-8595 


546-3549 


f 


101-7091 


823-2078 


i 


83-2522 


551-5459 


i 


102-1018 


829-5768 


1 


83-6449 


556-7615 


1 


102-4945 


835-9705 


1- 


84-0376 


562-0015 


f 


102-8872 


842-3886 


1 


84-4303 


567-2662 


1 


103-2799 


848-8314 


27 in. 


84-8230 


572-5553 


33 in. 


103-6726 


855-2986 


i 


85-2157 


577-8690 


^ 


104-0653 


861-7904 


1 


85-6084 


583-2072 


1 


104-4580 


868-3068 




86-0011 


588-5701 


i 


104-8507 


874-8477 


1. 


86-3938 


593-9574 


* 


105-2434 


881-4139 


1 


86-7865 


599-3693 


1 


105-6361 


888-0030 




87-1792 


604-8057 




106-0288 


894-6176 


^ 


87-5719 


610-2667 


r 


106-4215 


901-2567 



848 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



DIAM. 


CIROUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


34 in. 


106-8142 


907-9203 


40 in. 


125-6640 


1256-6370 


^ 


107-2069 


914-6084 


i 


126-0567 


1264-5032 


i 


107-5995 


921-3211 


JL 

4 


126-4494 


1272-3941 


1 


107-9922 


928-0584 


f 


126-8421 


1280-3094 


^ 


108-3849 


934-8202 


i 


127-2348 


1288-2493 


1 


108-7779 


941-6066 


1 


127-6275 


1296-2138 




109-1703 


948-4174 


1 


128-0202 


1304-2027 


1 


109-5630 


955-2529 


1 


128-4129 


1312-2163 


35 in. 


109-9557 


962-1127 


41 in. 


128-8053 


1320-2543 


1 


110-3484 


968-9973 


i. 


129-1983 


1328-3170 




110-7411 


975-9063 


\ 


129-5910 


1336-4041 


1 


111-1338 


982-8400 


1 


129-9837 


1344-5159 


1. 


111-5265 


989-7980 


i. 


130-3764 


1352-6520 


1 


111-9192 


996-7807 


1 


130-7691 


1360-8129 


1 


112-3119 


1003-7879 




131-1618 


1368-9981 


i 


112-7046 


1010-8197 


8 


131-5545 


1377-2080 


36 in. 


113-0974 


1017-8760 


42 in. 


131-9472 


1385-4424 


i 


113-4901 


1024-9568 


^ 


132-3399 


1393-7013 


4 


113-8826 


1032-0622 


I 


132-7326 


1401-9848 




114-2757 


1039-1922 


1 


133-1253 


1410-2929 


J. 


114-6680 


1046-3467 


i- 


133-5180 


1418-6254 


1 


115-0611 


1053-5257 


1 


133-9107 


1426-9826 


1 


115-4535 


1060-7293 




134-3034 


1435-3642 


1 ■ 


115-8465 


1067-9575 


1 


134-6961 


1443-7705 


37 in. 


116-2389 


1075-2101 


43 in. 


135-0888 


1452-2012 


1 


116-6316 


1082-4873 


J. 


135-4815 


1460-6565 


J. 


117-0242 


1089-7890 


X 


135-8742 


1469-1364 


1 


117-4179 


1097-1154 


1 


136-2669 


1477-6310 


1. 


117-8096 


1104-4662 


|. 


136-6596 


1486-1697 


1 


118-2027 


1111-8416 


1 


137-0523 


1494-7234 


f 


118-5951 


1119-2415 


1 


137-4450 


1503-3012 


1 


118-9881 


1126-6660 


1 . 


137-8377 


1511-9038 


38 in. 


119-3805 


1134-1149 


44 in. 


138-2304 


1520-5308 


i 


119-7735 


1141-5885 


^ 


138-6231 


1529-1825 


1 

4 


120-1659 


1149-0866 


1 


139-0158 


1537-8587 


f 


120-5589 


1156-6083 


1 


139-4085 


1546-5475 




120-9516 


1164-1564 


1. 


139-8012 


1555-2847 


1 


121-3443 


1171-7282 


1 


140-1939 


1564-0346 


1 


121-7370 


1179-3244 


1 


140-5866 


1572-8089 


i 


122-1297 


1186-9453 


1 


140-9793 


1581-6079 


39 in. 


122-5224 


1194-5906 


45 in. 


141-3717 


1590-4313 


J. 


122-9151 


1202-2605 


i 


141-7647 


1599-2777 


I 


123-3078 


1209-9550 


i 


142-1574 


1608-1518 


1 


123-7005 


1217-6740 


f 


142-5505 


1617-0390 


i 


124-0932 


1225-4175 


^ 


142-9428 


1625-9705 


1 


124-4859 


1233-1856 


1 


143.-3355 


1634-9267 




124-8786 


1240-9782 




143-7282 


1643-8874 


^ 


125-2713 


1248-7954 


1 ^ 


144-1209 


1652-8827 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



349 



DIAM. 


CIRCUM. 


AREA. 


DIAM. 


CIRCUM.. 


AREA. 


46 in. 


144-5133 


1661-9025 


52 in. 


163-3628 


2123-7166 


^ 


144-9060 


1670-9469 


i 


163-7555 


2133-9390 


I 


145-2987 


1680-0158 


i 


164-1482 


2144J.861 


f 


145-6914 


1689-0993 


f 


164-5409 


2154-4576 


i 


146-0841 


1698-2272 


i 


164-9336 


2164-7537 


1 


146-4768 


1707-3698 


1 


165-3263 


2175-0744 




146-8695 


1716-5368 




165-7190 


2185-4195 


1 


147-2622 


1725-7284 


1 


166-1117 


2195-7893 


47 in. 


147-6549 


1734-9445 


53 in. 


166-5044 


2206-1834 


8 


148-0476 


1744-1852 


^ 


166-8971 


2216-6022 




148-4403 


1753-4505 


1 


167-2898 


2227-0456 


f 


148-8330 


1762-7304 


1 


167-6825 


2237-5132 


i ■ 


149-2257 


1772-0546 


i 


168-0752 


2248-0059 


i 


149-6184 


1781-3936 


^ 


168-4679 


2258-5229 


f 


150-0111 


1790-7569 


i 


168-8606 


2269-0644 


i 


150-4038 


1800-1450 


i 


169-2533 


2279-6305 


48 in. 


150-7964 


1809-5574 


54 in. 


169-6460 


2290-2210 


i 


151-1891 


1818-9944 


i 


170-0387 


2300-8362 


4 


151-5818 


1828-4560 


i 


170-4314 


2311-4759 


f 


151-9745 


1837-9322 




170-8241 


2322-1392 




152-3672 


1847-4528 


1 


171-2168 


2332-8289 


1 


152-7599 


1856-9881 


1 


171-6095 


2343-5423 


f 


153-1526 


1866-5478 




172-0022 


2354-2801 


1 


153-5453 


1876-1322 


1 


172-3949 


2365-0426 


49 in. 


153-9380 


1885-7410 


55 in. 


172-7876 


2375-8294 


i 


154-3307 


1895-3744 


i 


173-1803 


2386-6411 


1 


154-7234 


1905-0323 




173-5730 


2397-4770 




155-1161 


1914-7150 


1 


173-9657 


2408-3377 


1 


155-5088 


1924-4218 


i 


174-3584 


2419-2227 


1 


155-9015 


1934-1534 


1 


174-7511 


2430-1775 


f 


156-2942 


1943-9095 


f 


175-1438 


2441-0666 


i 


156-6869 


1953-6902 


1 


175-5365 


2452-0254 


50 in. 


157-0796 


1963-4954 


56 in. 


175-9292 


2463-0086 


1 


157-4723 


1973-3251 


1 


176-3219 


2474-0145 


1 


157-8650 


1983-1794 


1 


176-7146 


2485-0489 


1 


158-2577 


1993-0583 


1 


177-1073 


2496-1059 


F . 


158-6504 


2002-9617 


i 


177-5000 


2507-1873 


1 


159-0431 


2012-8897 


1 


177-8927 


2518-2934 




159-4358 


2022-8421 




178-2854 


2529-4239 


1 


159-8285 


2032-8172 


1 


178-6781 


2540-5781 


51 in. 


160-2212 


2042-8206 


57 in. 


179-0708 


2551-7586 


^ 


160-6139 


2052-8467 


- i 


179-4635 


2562-9629 


1 


161-0066 


2062-8974 


i 


179-8562 


2574-1916 


1 


161-3993 


2072-9727 




180-2449 


2585-4450 


^ 


161-7920 


2083-0723 


I. 


180-6416 


2596-7227 


1 


162.1847 


2093-1966 


1 


181-0343 


2608-0251 


f 


162-5774 


2103-3554 


1 


181-4270 


2619-3520 


1 


162-9701 


2113-5188 


1 


181-8237 


2630-7035 



^50 



CIRCUMFERENCES AND AREAS OF CIRCLES. 



1 

DIAM. 


CIRCUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


58 in. 


182-2124 


2642-0794 


64 in. 


201-0620 


3216-9909 


i 


182-6051 


2653-4800 


i 


201-4547 


3229-5695 


1 

4 


182-9978 


2664-9051 


i 


201-8474 


3242-1707 


f 


183-3905 


2676-3549 


f 


202-2401 


3254-8005 


i 


183-7832 


2687-8289 


i 


202-6328 


3267-4527 


1 


184-1759 


2699-3277 


1 


203-0255 


3280-1296 


f 


184-5686 


2710-8508 


f 


203.4182 


3292-8309 


7 
8 


184-9613 


2722-3988 


1 


203-8109 


3305-5566 


59 in. 


185-3540 


2733-9710 


65 in. 


204-2035 


3318-3072 


^ 


185-7467 


2745-5681 


\ 


204-5962 


3331-0822 


1 


186-1394 


2757-1893 




204-9889 


3343-8818 


f 


186-5321 


2768-8355 


1 


205-3816 


3356-7059 


i 


186-9248 


2780-5059 


i 


205-7743 


3369-5545 


1 


187-3175 


2792-2010 


1 


206-1670 


3382-4277 


f 


187-7102 


2803-9205 


f 


206-5597 


3395-3253 


i 


188-1029 


2815-6647 


1 


206-9524 


3408-2476 


60 in. 


188-4956 


2827-4334 


66 in. 


207-3451 


3421-1944 


i 


188-8883 


2839-2266 , 


i 


207-7378 


3434-1657 


i 


189-2810 


2851-0444 


i 


208-1305 


3447-1616 


f 


189-6737 


2862-8868 ^ 


1 


208-5232 


3460-1820 


i 


190-0664 


2874-7536 




208-9159 


3473-2270 


1 


190-4591 


2886-6450 


1 


209-3086 


3486-3966 


f 


190-8518 


2898-5610 


1 


209-7013 


3499-3906 


i 


191-2445 


2910-5016 


1 


210-0940 


3512-5093 


61 in. 


191-6372 


2922-4666 


67 in. 


210-4867 


3525-6524 


1 


192-0299 


2934-4562 


i 


210-8794 


3538-8201 


1 


192-4226 


2946-4703 


i 


211-2721 


3552-0123 


1 


192-8153 


2958-5091 


f 


211-6648 


356.5-2292 


i 


193-2080 


2970-5722 


* 


212-0575 


3578-4704 


1 


193-6007 


2982-6600 


1 


212-4502 


3591-7363 


f 


193-9934 


2994-7723 


1 


212-8429 


3605-0267 


1 


194-3861 


3006-9092 


i 


213-2356 


3618-3417 


62 in. 


194-7788 


3019-0705 


68 in. 


213-6283 


3631-6811 


i 


195-1715 


3031-2560 


i. 


214-0210 


3645-0451 


1 


195-5642 


3043-4670 


1 


214-4137 


3658-4337 


1 


195-c)569 


3055-7021 


1 


214-8064 


3671-8469 


i 


196-3396 


3067-9616 


i. 


215-1991 


3*85-2845 


1 


196-7423 


3080-2458 


1 


215-5918 


3698-7468 


1 


197-1350 


3092-5544 


f 


215-9845 


3712-2335 


i 


197-5277 


3104-8877 


1 


216-3772 


3725-7450 


63 in. 


197-9204 


3117-2453 


69 in. 


216-7699 


3739-2807 


1 


198-3131 


3129-6273 


X 


217-1626 


3752-8411 


1 


198-7058 


3142-0344 


1 


217-5553 


3766-4260 


1 


199-0985 


3154-4659 


1 


217-9480 


3780-0356 


i 


199-4912 


3166-9217 


i 


218-3407 


3793-6695 


1 


199-8839 


3179-4022 


1 


218-7334 


3807-3281 


1 


200-2766 


3191-9072 


f 


219-1261 


3821-0112 


i 


200-6693 


3204-4368 


i 


219-5189 


3834-7189 



CIRCUMFERENCES AND AREAS OF CIRCLES. 3ol 



DIAM. 


CIRCUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


70 in. 


219-9115 


3848-4510 


76 in. 


238-5611 


4536-4598 


^ 


220-3042 


3862-2077 


i 


239-1538 


4551-3946 


1 


220-6969 


3875-9890 


1 


239-5464 


4566-3540 


1 


221-0896 


3889-7948 


1 


239-9392 


4581-3379 


^ 


221-4823 


3903-6252 




240-3319 


4596-3464 


1 


^'221-8750 


3917-4802 


1 


240-7246 


4611-3895 


1 


222-2677 


3931-3596 


f 


241-1173 


4626-4370 


f 


222-6604 


3945-2636 


i 


241-5100 


4641-5192 


71 in. 


223-0531 


3959-1921 


77 in. 


241-9047 


4656-6257 


i 


223-4458 


3973-1452 


i 


242-2954 


4671-7569 


i 


223-8385 


3987-1229 


JL 


242-6861 


4686-9126 




224-2312 


4001-1252 


1 


243-0808 


4702-0929 


1 


224-6239 


4015-1518 


1 


243-4735 


4717-2977 


1 


225-0166 


4029-2031 


1 


243-8662 


4732-5271 




225-4093 


4043-2788 


f 


244-2589 


4747-7810 


1 


225-8020 


4057:3884 


i 


244-6516 


4763-0595 


72 in. 


226-1947 


4071-5041 


78 in. 


245-0443 


4778-3624 


i 


226-5874 


4085-6532 


i 


245-4370 


4793-6890 




226-9801 


4099-8275 


l 


245-8297 


4809-0420 


1 


227-3728 


4114-0260 




246-2224 


4824-4187 


1 


227-7655 


4128-^490 


1 


246-6151 


4839-8198 


1 


228-1582 


4142-4967 


1 


247-0078 


4855-2455 




228-5509 


4156-7689 


f 


247-4005 


4870-7958 


1 


228-9436 


4171-0656 


1 


247-7932 


4886-1707 


73 in. 


229-3363 


4185-3868 


79 in. 


248-1859 


4901-6669 


i 


229-7290 


4199-7326 


i • 


248-5786 


4917-1938 


1 


230-1217 


4214-1029 


1 


248-6713 


4932-7423 




230-5144 


4228-4979 


3 


249-3640 


4948-3154 


1 


230-9071 


4242-9171 


1 


249-7567 


4963-9127 


1 


231-2998 


4257-3611 


1 


250-1494 


4979-5310 




231-6925 


4271-8296 


f 


250-5421 


4995-1814 


1 


232-0852 


4286-3227 


1 


250-9348 


5010-8526 


74 in. 


232-4779 


4300-8404 


80 in. 


. 251-3275 


5026-5482 


i 


232-8706 


4315-3826 


i 


251-7202 


5042-2785 


1 


233-2633 


4329-9492 


J. 


252-1129 


5058-0133 




233-6560 


4344-5405 


1 


252-5056 


5073-7826 


J. 


234-0487 


4359-1563 


J. 


252-8983 


5089-5764 


1 


234-4414 


4373-7967 


1 


253-2910 


5105-3948 




234-8341 


4388-4613 


f 


253-6837 


5121-2378 


1 


235-2268 


4403-1508 


1 


254-0764 


5137-1054 


75 in. 


235-6195 


4417-8647 


81 in. 


254-4691 


5152-9978 


i 


236-0122 


4432-6032 


i 


254-8618 


5168-9140 


1 

4 


236-4049 


4447-3662 


1 

4 


255-2545 


5184-8551 


f 


236-7976 


4462-1539 


1 


255-6472 


5200-8208 


i 


237-1903 


4476-9659 


i 


256-0399 


5216-81()9 


1 


237-5830 


4491-8026 


1 


256-4326 


5232-8258 


1 


237-9757 


4506-6637 


5. 

4 


256-8252 


5248-8650 


1 


238-3684 


4521-5495 


1 


257-2180 


5264.9289 



852 



CIRCUMFEnEXCES AND AREAS OF CIRCLES. 



DIAM. 


CIRCUM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


82 in. 


257-6106 


5281-0172 


88 in. 


276-4602 


6082-1234 


i 


258-0033 


5297-1302 


i 


276-8529 


6099-4145 


i 


258.3960 


5313-2677 


i 


277-2456* 


5116-7300 




258-7887 


5329-4297 


f 


277-6383 


6134-0702 


i 


259-1814 


5345-6162 


i 


278-0310 


6151-4349 


1 


259-5741 


5361-8273 


1 


278-4237 


* 6168-8240 


f 


259-9668 


5378-0630 


3. 

4 


278-8164 


6186-2377 


1 


260-3595 


5394-3233 


8 


279-2091 


6203-6751 


83 in. 


260-7522 


5410-6079 


89 in. 


279-6018 


6221-1389 


i 


261-1449 


5426-9172 


i. 


279-9945 


6238-6263 


J. 


261-5376 


5443-2511 


i 


280-3872 


6256-1382 


1 


261-9303 


5459-6096 


1 


280-7799 


6273-6746 




262-3230 


5475-9923 


i 


281-1726 


6291-2356 


1 


262-7157 


5492-3998 


1 


281-5653 


6308-8212 


I 


263-1084 


5508-8318 


1 


281-9580 


6326-4313 


i 


263-5011 


5525-2884 


i 


282-1507 


6344-0660 


84 in. 


263-8938 


5541-7694, 


90 in. 


282-7434 


6361-7251 


i 


264-2865 


5558-2751 


1 


283-1361 


6379-4069 




264-6792 


5574-8053 


1 


283-5288 


6397-1171 


1 


265-0719 


5591-3600 


1 


283-9215 


6414-8499 


J. 


265-4646 


5607-9392 


^ 


284-3142 


6432-6073 


1 


265-8572 


5624-5430 


1 


284-7069 


6450-3893 


f 


266-2500 


5641-1714 


I 


285-0996 


6468-1954 


i 


266-6427 


5657-8236 


1 


285-4923 


6486-0265 


85 in. 


267-0354 


5674-5017 


91 in. 


285-8850 


6503-8821 


1 


267-4281 


5691-2037 


i 


286-2777 


6521-7622 




267-8208 


5707-9302 


i 


286-6704 


6539-6669 


1 


268-2135 


5724-6814 




287-0631 


6557-5962 


i 


268-6062 


5741-4569 


i 


287-4558 


6575-5498 


1 


268-9989 


5758-2631 


1 


287-8485 


6593-5281 


a 


269-3916 


5775-0818 


f 


288-2412 


6611-5308 


1 


269-7843 


5791-9311 


f 


288-6339 


6629-5582 


86 in. 


270-1770 


5808-8048 


92 in. 


289-0266 


6647-6100 


i 


270-5696 


5825-7032 


i 


289-4193 


6665-6865 




270-9624 


5842-6260 


i 


289-8120 


6683-7875 


1 


271-3551 


5859-5735 


1 


290*-2047 


6701-9131 


1 


271-7478 


5876-5454 


i 


290-5974 


6720-0630 


1 


272-1405 


5893-5420 


1 


290-9901 


6738-2377 


1 


272-5332 


5910-5630 


f 


291-3828 


6756-4368 


i 


272-9259 


5927-6087 


1 


291-7755 


6774-6605 


, 87 in. 


273-3186 


5944-6787 


93 in. 


292-1682 


6792-9087 


i 


273-7113 


5961-7734 


i 


292-5609 


6811-1814 


1 


274-1040 


5978-8926 


1 

4 


292-9536 


6829-4788 


1 


274-4967 


5996-0365 


1 


293-3463 


6847-8007 


i 


274-8894 


6013-2047 


i 


293-7390 


6866-1471 


1 


275-2821 


6030-3975 


1 


294-1317 


6884-5182 


1 


275-6748 


6047-6149 


1 


294-5244 


6902-9135 


1 


276-0675 


6064-8569 


1 


294-9171 


6921-3336 



CIRCUMFERENCES AND AREAS OF ?CIRCLES. 853 



DIAM. 


CIRCUxM. 


AREA. 


DIAM. 


CIRCUM. 


AREA. 


94 in. 


295-3097 


6939-7782 


97 in. 


304-7345 


7389-8113 


i 


295-7024 


6958-2474 


i 


305-1272 


7408-8695 


JL 


296-0951 


6976-7410 


J. 

4 


305-5299 


7427-9522 


1 


296-4878 


6995-2593 


t 


305-9126 


7447-0595 


X 


^96-8805 


7013-8019 


i 


306-3033 


7466-1913 


1 


297-2732 


7032-3693 


1 


306-6980 


7485-3478 


f 


297-6659 


7050-9612 


1 


307-0907 


7504-5285 


i 


298-0586 


7069-5777 


1 


307-4834 


7523-7340 


95 in. 


298-4513 


7088-2184 


98 in. 


307-8761 


7542-9640 


i 


298-8440 


7106-8839 


i 


308-2688 


7562-2186 


i 


299-2367 


7125-5799 


1 

4 


308-6615 


7581-4976 




299-6294 


7144-2886 


f 


309-0542 


7600-8012 


i 


300-0221 


7163-0276 


i 


309-4469 


7620-1293 


1 


300-4148 


7181-7914 


1 


309-8396 


7639-4810 


f 


300-8075 


7200-5794 


1 


310-2323 


7658-8593 


i 


301-2002 


7219-3921 


1 


310-6250 


7678-2610 


96 in. 


301-5929 


7238-2295 


99 in. 


311-0177 


7697-6874 


i 


301-9856 


7257-0914 


i. 


311-4104 


7717-1383 


i 


302-3783 


7275-9777 


1 


311-8031 


7736-6137 




302-7710 


7294-8886 


f 


312-1958 


7756-1137 


1 


303-1637 


7313-8240 


i 


312-5885 


7775-6382 


1 


303-5564 


7332-7841 


1 


312-9812 


7795-1873 


f 


303-9491 


7351-7686 


f 


313-3739 


7814-7608 


1 


304-3418 


7370-7777 


1 


313-7666 


7834-3590 








. 100 in. 


314-1593 


7853-9816 



Note. — This Table* has been calculated by the following process : 

1. To find the Circumferences. — Add -392699 to any of those pre- 
viously found, and it will give the next in succession. 

2. To find the Areas. — Having calculated two in succession to 
eight places of decimals, take their difference, to which add -02454369, 
and add the result to the last found area, and cut off the last four 
figures, and it will give the next ; and so on. 



854 



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KNOT-TABLE. 



TABLE K. 

Knot- Table. 

The mifrhlto^ and seconds of time in which a vessel passes over the mea- 
sured knot being known, look for the corresponding number in this 
Table, which Tvill be the rate of the vessel in knots. 



Sec. 


3m 


4ni 


Quo 1 6m 


7m 


8m 


9m 


10m 


llm 


12m 


13m 


14m 





20-000 


15-000 


12-000 


XO-000 


8-571 


7-500 


6-666 


6-000 


5-464 


5-000 


4-616 


4-285 


1 


19-890 


14-938 


11-960 


5-972 


8-551 


7-484 


6-654 


5-990 


5-446 


4-993 


4-609 


4-280 


2 


19-780 


14-876 


11-920 


9-&.i4 


8-530 


7-468 


6-642 


5-980 


5-438 


4-986 


4-603 


4-275 


3 


19-672 


14-815 


11-880 


9-917 


8-510 


7-453 


6-629 


5-970 


5-429 


4-979 


4-597 


4-270 


4 


19-564 


14-754 


11-841 


9-890 


8-490 


7-438 


6-617 


5-960 


5-421 


4-972 


4-591 


4-265 


5 


19-460 


14-694 


11-803 


9-863 


S-470 


7-422 


6-605 


5-950 


5-413 


4-965 


4-585 


4-260 


6 


19-355 


14-634 


11-764 


9-830 


8-^50 


7-407 


6-693 


6-940 


5-405 


4-958 


4-580 


4-255 


7 


19-251 


14-576 


11-726 


9-809 


8-4S!) 


7-392 


6-681 


6-930 


5-397 


4-951 


4-574 


4-250 


8 


19-150 


14-516 


11-688 


9-783 


8-413 


7-377 


6-569 


6 921 


5-389 


4-945 


4-568 


4-245 


9 


19-047 


14-457 


11-650 


9-766 


8-391 


7-362 


6-557 


6-911 


5-381 


4-938 


4-562 


4-240 


10 


18-947 


14-400 


11-613 


9-729 


8-372 


7-346 


6-546 


5-901 


5-373 


4-931 


4-556 


4-235 


11 


18-848 


14-342 


11-575 


9-703 


8-352 


7-331 


6-633 


5-891 


5-365 


4-924 


4-551 


4-230 


12 


18-750 


14-285 


11-538 


9-677 


8-333 


7-317 


6-621 


5-882 


5-367 


4-918 


4-546 


4-225 


13 


18-652 


14-220 


11-501 


9-651 


8-314 


7.302 


6-609 


5-872 


5-349 


4-911 


4-539 


4-220 


14 


18-656 


14-173 


11-465 


9-625 


8-295 


7-287 


6-498 


6-863 


5-341 


4-904 


4-534 


4-215 


15 


18-401 


14-118 


11-428 


9-600 


8-275 


7-272 


6-486 


5-863 


5-333 


4-897 


4-528 


4-210 


16 


18-367 


14-063 


11-392 


9-574 


8-266 


7-258 


6-474 


5-844 


5-325 


4-891 


4-522 


4-206 


17 


18-274 


14-008 


11-356 


9-549 


8-238 


7-243 


6-463 


5-834 


^-317 


4-884 


4-516 


4-201 


18 


18-181 


13-953 


11-323 


9-524 


8-219 


7-229 


6-451 


5-826 


6-309 


4-878 


4-511 


4-196 


19 


18-090 


13-900 


11-285 


9-490 


8-200 


7.214 


6-440 


5-815 


5-301 


4-871 


4-505 


4-191 


20 


18-000 


13-846 


11-250 


9-473 


8-181 


7-200 


6-428 


6-806 


5-294 


4-864 


4-500 


4-186 


21 


17-910 


13-793 


11-214 


9-448 


8-163 


7-185 


6-417 


5-797 


5-286 


4.858 


4-494 


4-181 


22 


17.823 


13-740 


11-180 


9-424 


8-144 


7-171 


6-406 


5-787 


5-278 


4-851 


4-488 


4-176 


23 


17-734 


13-688 


11-145 


9-399 


8-127 


7.157 


6-394 


6-778 


5-270 


4-845 


4-483 


4-171 


24 


17-647 


13-636 


11-111 


9-376 


8-108 


7-142 


6-383 


5-769 


6-263 


4-838 


4-477 


4-166 


25 


17-560 


13-584 


11-077 


9-350 


8-090 


7-128 


6-371 


5-760 


6-255 


4-832 


4-472 


4-161 


26 


17-475 


13-533 


11-043 


9-326 


8-071 


7-114 


6-360 


5-750 


5-247 


4825 


4-466 


4-157 


27 


17-391 


13-483 


11-009 


9-302 


8-053 


7-100 


6-349 


5-741 


5-2^10 


4-819 


4-460 


4-152 


28 


17-307 


13-432 


10-976 


9-278 


8-035 


7-086 


6-338 


5-732' 


6-232 


4-812 


4-465 


4-147 


29 


17-225 


13-383 


10-942 


9-264 


8-017 


7-072 


6-327 


5-723 


6-224 


4-806 


4-449 


4-142 


30 


17-143 13 333 


10-909 


9-230 


8-000 


7-059 


6316 


5-714 


6-217 


4-800 


4.444 


4-137 


31 


17-061 13-284 


10-876 


9-207 


7-982 


7-046 


6-304 


5-705 


5-210 


4-793 


4-438 


4-133 


32 


16-981 


13-235 


10-843 


9-183 


7-964 


7-031 


6-283 


5-696 


5-202 


4-787 


4.433 


4-128 


83 


16-901 


13-186 


10-810 


9-160 


7-947 


7-017 


6-282 


5-687 


5-195 


4-780 


4-428 


4-123 


34 


16-822 


13-138 


10-778 


9-137 


7-929 


7-004 


6-271 


5-678 


5-187 


4-774 


4-422 


4-118 


35 


16-744 


13-092 


10-764 


9-113 


7-912 


6-990 


6-260 


5-669 


5-179 


4-768 


4-417 


4-114 


36 


16-667 


13-043 


10-714 


9-090 


7-895 


6-977 


6-250 


5-666 


5-172 


4-761 


4-411 


4-110 


37 


16-590 


12-996 


10-682 


9-068 


7-877 


6-963 


6-239 


5-651, 


6-164 


4-755 


4-406 


4-105 


38 


16-514 


12-960 


10-651 


9-044 


7-860 


6-950 


6-228 


5-642 


5-167 


4-749 


4-400 


4-100 


39 


16-438 


12-903 


10-619 


9-022 


7-843 


6-936 


6-217 


5-633 


5-160 


4-743 


4-395 


4-095 


40 


16-363 


12-857 


10-588 


9-000 


7-826 


6-923 


6-007 


5-625 


6-142 


4-738 


4-390 


4-090 


41 


16-289 


12-811 


10-567 


8-977 


7-809 


6-909 


6-196 


5-616 


5-135 


4-730 


4-384. 


4-086 


42 


16-216 


12-766 


10-526 


8-965 


7-792 


6-896 


6-185 


5-607 


5-128 


4-724 


4-379 


4-081 


43 


16-143 


12-711 


10-496 


8-933 


7-775 


6-883 


6-174 


5-698 


5-121 


4-718 


4-374 


4-077 


44 


16-071 


12-676 


10-466 


8-911 


7-758 


6-870 


6-164 


5-590 


5-114 


4-712 


4-368 


4-072 


45 


16-000 


12-631 


10-434 


8-889 


7-741 


6-857 


6-153 


5-581 


5-106 


4-706 


4-363 


4-067 


46 


15-929 


12-587 


10-404 


8-867 


7-725 


6-844 


6-143 


5-572 


5-099 


4-700 


4-358 


4-063 


47 


15-859 


12-543 


10-375 


8-846 


7-708 


6-831 


6-132 


5-664 


5-091 


4-693 


4 353 


4-058 


48 


15-789 


12-500 


10-345 


8-823 


7-692 


6-818 


6-122 


5-655 


5-084 


4-687 


4-347 


4-054 


49 


15-721 


12-466 


10-316 


8-801 


7-975 


6-805 


6-112 


5-547 


5-077 


4-681 


4-342 


4-049 


50 


15-652 


12-413 


10-286 


8-780 


7-659 


6-792 


6-101 


5-538 


5-070 


4-675 


4-337 


4-044 


51 


15-584 


12-371 


10-266 


8-759 


7-643 


6-779 


6-091 


5-530 


5-063 


4-669 


4-332 


4-040 


52 


15-517 


12-329 


10-227 


8-737 


7-627 


6-766 


6.081 


5-521 


5-066 


4-663 


4-326 


4-035 


53 


15-450 


12-287 


10-198 


8-716 


7-611 


6-754 


6-071 


6-613 


5-049 


4-657 


4-321 


4-031 


54 


15-384 


12-245 


10-169 


8-695 


7-696 


6-741 


6-060 


5-504 


5-042 


4-651 


4-316 


4-026 


55 


15-319 


12-203 


10-140 


8-675 


7-679 


6-729 


6-050 


6-496 


5-035 


4-645 


4-311 


4-022 


56 


15-254 


12-162 


10-112 


8-664 


7-563 


6-716 


6-040 


5-487 


5-028 


4-639 


4-306 


4-017 


57 


15-190 


L2-121 


10-084 


8-633 


7-547 


6-704 


6-030 


5-479 


6-020 


4-633 


4-301 


4-013 


58 


15-125 


12-080 


10-055 


8 612 


7-531 


6-691 


6-020 


5-471 


5-013 


4-627 


4-295 


4-008 


59 


15-062 


12-040 


10-027 


8-591 


7.516 


6-679 


6-010 


5-463 


6-006 


4-621 


4-290 


4-004 



LIST OF SCBEW STEJ^MEE* 



List of Screw Steamers in her Majesty's Navy. 



Name of Ship. 



Aboukir .... 
Adventure, 
^tna 



Ajax 

Alacrity.. 

Alert 

Algerine.. 
Algiers ..., 
Amphion . 

Anson 

Ai'cher .... 
Ariadne .. 

Ariel 

Arrogant.. 
Arrow 



Assurance. 

Atlas 

Aurora 

Bacchante. 



Barrosa ■ 



Bee 

Black Prince., 

Blenheim , 

Brisk 

Brunswick .... 

Buffalo 

Bulwark , 

Caesar 

Cadmus, 

Cameleon 

Cetfturion .... 
Challenger.... 

Charybdis 

Chasseur 

Chesapeake... 

Clio 

Colossus 

Conflict 

Conqueror.... 

Coquette , 

Cordelia 

Cormorant.... 
Cornwallis — 

Cossack 

Cressy 

Cruiser 

Curacoa 

Curlew 

Cygnet 

Dart 

Dauntless 

Defiance , 

Desperate 

Diadem.., 

Donegal 

Doris 



400 
400 
200 
600 
450 
200 
100 

80 
600 
300 
800 
202 
800 

60 
360 
160 
400 
200 
800 
400 
600 

400 
160 
10 
1250 
450 
250 
400 



Maker of Engines. 



Penn and Son. 
Fawcett. 



Penn and Son. 
Maudslay and Field. 
Ravenhill and Salkeld. 
Ditto. 



Maudslay and Field. 
Ravenhill and Salkeld. 
Maudslay and Field. 
Ravenhill and Salkeld. 
Maudslay and Field. 
Ravenhill and Salkeld. 
Penn and Son. 
Humphrey & Tennant. 
Fawcett. 

Ravenhill and Salkeld. 
Maudslay and Field. 

Ditto. 

Ditto. 



Humphrey & Tennant. 

Maudslay and Field. 

Penn and Son. 

Seaward. 

Scott and Sinclair. 

Ravenhill and Salkeld. 



Penn and Son. 

Ditto. 
Maudslay and Field. 
Ravenhill and Salkeld. 
Penn and Son. 
Ravenhill and Salkeld. 



Maudslay and Field. 
Ravenhill and Salkeld. 
Penn and Son. 
Seaward. 
Penn and Son. 
Ravenhill and Salkeld. 



Napier. 
Penn and Son. 
Maudslay and Field. 

Ditto. 
Rennie. 
Maudslay and Field. 

Ditto. 
Napier. .. 

Ditto. 

Ditto. 
Maudslay and Field. 

Ditto. 

Ditto. 
Penn and Son. 

Ditto. 









Screw. 1 


o . 

ll 

s >> 


1% 


1! 






4, 


1 
1 


Jq 


sT' 


1- 


i 


1 


in. 


ft.in 




ft. in. 


ft. in. 


58 


3 3 


60 


18 


17 


45 


3 


... 


22 7K 


17 214 


70% 


3"'6 


60 


20" 6 


18 "b 


55 


2 


48 


18 


16 


45 


2 


86 


16 


11 


32 


2 


75 


12 


10 


76 


3""6 


45 


25 6 


i8*"b 


48 


3 


45 


21 


15 


82 


4 


45 


27 6 


19 


54 


3 


41 


7 3 


9 


82 


3 8 


50 


27 6 


20 


2b% 


1 9 


81 


10 9 


9 


55 


3 


61 


15 2 


15 6 


42 


1 9 


93 


14 


11 


45 


3 




22 7K 


17 214 


45 


2 


87 


16 


11 


82 


4 


45 


27 6 


19 


64 


3 


50 


22 6 


17 


76 


3 6 


45 


25 6 
to 28 6 


19 4 


42 


l""9 


86 


14 


11*"6 


20 


2 


40 


5 


4 


10414 


4 


54 


24 6 




52 


3 


43 


20 


16 


152 


3 6 


34 


12 


12 


64 


3 


53 5 


20 7 


17 


58 


3""3 


60 


18 lb 


17 ""6 


58 


3 3 


58 


23 6 


16 


45 


2 


75 


15 


12 4 


64 


3 


54 


21 


17 1 


58 


3 3 


67 


23 6 


16 


64 


3 


40 


26 


16 


64 


3 


50 


22 6 


17 "b 


64 


3 


50 


26 


16 


58 


3 3 


60 


18 6 


17 1 


46^4 


2 


64 


20 


13 7 


82 


4 


55 


26 


19 


45 
45 


2 
2'""o 


82^ 
86 


16 
16 


11 

ii"b 


30H 


2 6 


103 


9 6 


12 


51 


2 3 


64 ■ 


16 7 


12 1 


64 


3 


55 


21 


17 


28 


2 


53 


6 9 


9 


57H 


2 9 


64 


20 1 


14 2 


27 


2 


53 


8 1 


9 


32 


1 6 


106 


11 4 


9 


32 


1 6 


106 


11 4 


9 


84 


4 


31 


16 4 


14 9 


82 


4 


45 


27 6 


19 


55 


2 6 


3414 


14 


13 


82 


4 


54 


31 to 33 


18 


82 


4 


52 


28 6 


19 


82 


4 


53 


30 


20 



Remarks. 






S,oti 



''til 

3.2 



g «3 p 
O a> O 
ll§2 






o^S^ ft a 



Fitted with screw 
and paddle. 



Floating factory. 



High pressure. 



Multiple 2-3 to 1 



358 



LIST OF SCREW STjEAMERS. 



Name of Ship. 



Duke of Wel- 
lington 

Duncan 

Eclipse 

Edgar 

Edinburgh 

Emerald 

Encounter 

Krebus 

Esk 

Espoir 

Eurotas 

Euryalus 

Exmouth 

Fairy 

Falcon 

Fawn 

Flying-fish 

Forth 

Fox 

Foxhound 

Frederick Wil- 
liam 

Galatea 

Gannett 

Gibraltar 

Glasgovf 

Glatton 

Goliath 

Grayhound 

Griflfon 

Hannibal 

IlaiTier 

Hastings 

Hawke 

Hero 

Hesper 

Highflyer 

Himalaya 

Hogue 

Hood 

Horatio 

Hornet 

Howe 

Icarus 

ImmortaUte ... 

Imperieuse 

Industry 

Intrepid 

Irresistible 

James Watt.... 

Jason 

Jasper 

Landrail 

Lapwing 

Lee 

LeTen 

Liffey 

LiUy 

Lion 

Liverpool 

London 

Lynx 

Lyra 

Majestic 



200 
600 
450 
600 
360 
200 
250 
80 
200 
400 
400 
128 
100 
100 
350 
200 
200 
200 

500 
800 
150 
800 
600 
150 
400 
200 
80 
450 
100 
200 
200 
600 
120 
250 
700 
450 
600 
250 
100 
1000 
150 
600 



Maker of Engines. 



Napier, 

Penn and Son. 

Napier. 

Maudslay and Field. 

Ditto. 
Ravenhill and Salkeld. 
Penn and Son. 
Napier. 
Scott Russell. 



Penn and Son. 

Ditto. 
Maudslay and Field. 
Penn and Son. 
P^avenhill and Salkeld. 

Ditto. 
Maudslay and Field. 
Penn and Sou. 
Ravenhill and Salkeld. 
Humphrey & Tennant. 

Maudslay and Field. 
Penn and Son. 
Ravenhill and Salkeld. 
Maudslay and Field. 
Ravenhill and Salkeld. 

Ditto. 
Penn and Son. 
Ravenhill and Salkeld. 
Napier. 

Scott and Sinclair. 
Humphrey & Tennant. 
Maudslay and Field. 
Penn and Son. 
Maudslay and Field. 



Maudslay and Field. 
Penn and Son. 
Seaward. 

Maudslay and Field. 
Seaward. 

Boulton and Watt. 
Penn and Son. 
Humphrey & Tennant. 
Maudslay and Field. 



Penn and Son. 



Maudslay and Field. 
Penn and Son. 
Boulton and Watt. 
Ravenhill and Salkeld. 
Maudslay and Field. 
Humphrey & Tennant. 
Ravenhill and Salkeld. 
Napier. 



Penn and Son. 
Napier. 
Penn and Son. 
Humphrey & Tennant. 
Penn and Son. 

Ditto. 
Ravenhill and Salkeld. 
Mauds lav and Field. 



<l-l 








Screw. 1 




II 


m ® 
1.1 
IS 








,d 


1 


.go 


^^ 


S^ 


a 


ei 


"^ 


^ 




A 


s 


in. 


ft.in 




ft. 


in. 


ft. in. 


93% 


4 6 


30 


16 


3 


18 


82 


4 


55 


26 





19 


45 


2 


86 


15 


& 


11 


76 


3 6 


45 


26 





18 


55 


2 6 


54 


18 


9 


16 


76 


3 6 


45 


28 





18 


55 


2 3 


82 


16 


9 


12 


32 


2 2 




13 


6 


8 


50 


2 9 


68 


17 


1 


12 2>^ 


30i< 


2 6 


100 


12 





10 "0 


58 


3 3 


57 


21 





17 


64 


3 


53 


21 





17 


42 


3 


40 


8 





6 6 


32 


2 


80 


11 


9 


10 


32 


2 


75 


12 





10 


53 


2 3 


82 


20 


6 


11 


30^ 


2 6 


110 


10 





12 


45 


2 


75 


11 10 


12 1 


42% 


1 9 


93 


14 


3 


11 


66 


3 6 


50 


21 





18 


82 


3 8 


58 


28 


6 


20 


39 


2 


75 


14 


6 


10 


82 


4 


45 


27 


6 


19 


76 


3 6 


45 


26 





18 


25J^ 


2 


127 


14 





6 3 


58 


3 3 


R5 


18 


6 


17 


45 


2 


75 


14 


6 


12 


32 


1 6 


1U6 


11 


4 


9 


71% 


4 


27-5 


12 


6 


17 


34 


1 9 


93 


10 





10 


30 


2 6 


78 


12 


3 


12 


30 


2 6 


80 


9 


6 


12 


76 


3 6 


45 


26 


6 


19 


5514 


2""6 


50K 


9 


8 


13 "b 


77% 


3 6 




.. 






3 


47 


21 


1 


16 1 


76 


3 6 










54 


3 


41% 


13 





14 


38 


2 


71 


13 


6 


10 


92^ 


4 


54 


28 





20 


76 


3 6 


45 


25 


6 










to 










29 


6 


19 5 


55 


3 


68 


16 





16 


58% 


2""3 


77 


21" 


"3 


11 "b 


58 


3 3 


66 


17 





17 


52 


3 


54 


24 


4 


17 


64 


3 


50 


26 





16 


18 


1 6 




8 





6 6 


32 


1 4 




9 


6 


9 


45 


2 


35 


15 


7 


11 


32 


1 6 


106 


11 


4 


9 


70K 


3"'6 


57 


25" 


"e 


18"b 


45 


2 


86 


16 


6 


11 


58 


3 3 


43 


18 





17 


76 


3 3 




22 


6 


18 


71 


3 


50 


20 





18 


35% 


1 8 


113 


9 


8% 


11 


25K 


1 9 


80 


11 





9 


64 


3 


50 


21 





17 



Kemarks. 



High pressure. 
High pressure. 
Multiple 5 to 1. 

High pressure. 



High pressure. 



Multiple not 
known. 



Fitted with 
screw of an in- 
creasing pitch. 



Not tried. 



LIST OF SCREW STEAMERS. 



359 



Name of Ship. 



Malacca 

Marlborough . 
Mars 



Megaera 

Melpomene 

Mersey 

Meteor 

Minx 

Miranda 

Mohawk 

MuUett 

Mutine 

Narcissus 

Nelson 

Neptune 

Newcastle 

Niger 

Nile 

Nimrod 

Octavia 

Orestes 

Orion 

Orlando 

Orpheus 

Osprey 

Pantaloon 

Pearl 

Pelican 

Pelorus 

Pembroke 

Penguin 

Perseverance... 

Phaeton... 

Phoebe 

Phoenix 

Philomel 

Pioneer 

Plover 

Plumper 

Prince ofWales 
Princess Royal 

Plyades ,. 

Queen 



Racer 

Racehorse. 

Racoon 

Ranger .... 
Renown... 
Repulse.... 
Revenge... 
Reynard... 
Rifleman .. 



Rinaldo 

Ringdove ....... 

Rodney 

Roebuck , 

Rosario ..... — 
Royal Albert.. 
Royal George. 

Sove- 



Royal 

reign 
Royal William 
Russell 



200 
800 
400 
400 
350 
600 

1000 
150 
10 
250 
200 
80 
200 
400 
500 
500 
600 
400 
500 
175 
500 
400 
600 

1000 
400 
200 
150 
400 
200 
400 
200 



350 



Maker of Engines. 



Penn and Son. 
Maudslay and Field. 

Ditto. 
Penn and Son. 
Rennie. 
Penn and Son. 
Maudslay and Field. 

Ditto. 
Seaward. 
Napier. 

Humphrey & Tennant. 
Napier. 

Maudslay and Field. 
Ravenhill and Salkeld. 

Ditto. 

Ditto. 

Ditto. 
Maudslay and Field. 
Seaward. 
Maudslay and Field. 

Ditto. 



Penn and Son. 

Ditto. 
Humphrey & pennant. 
Maudslay and Field. 



Penn and Son. 
Ravenhill and Salkeld. 

Ditto. 
Maudslay and Field. 
Napier. 

Penn and Son. ' 
Boulton and Watt. 
Napier. 
Penn and Son. 
Napier. 

Ravenhill and Salkeld, 
Napier. 

Ditto. 
Penn and Son. 

Ditto. 

Ditto. 
Maudslay and Field. 

Humphrey & Tennant. 

Napier. 

Ravenhill and Salkeld. 

Rennie. 

Penn and Son. 



Maudslay and Field. 
Humphrey <fe Tennant, 
Ravenhill and Salkeld. 

Humphrey & Tennant. 
Ravenhill and Salkeld. 
Maudslay and Field. 
Ravenhill and Salkeld. 



Penn and Son. 
Ditto. 



Maudslay and Field. 

Napier 

Penn and Son. 



4 



82 4 
65 3 
30 2 6 



45 



Screw. 



75 



ft. in. 



58^ 
4 541^ 28 



20 


6 


11 





23" 


"6 


18 


"0 


32 


6 


20 





20 





16 





16 





11 






20 5 



26 to 28 

22 

9 6 



ft in, 

13 6 

19 1 
17 

17 

14 6 

18 

20 
6 
4 1 

12 

11 
9 

12 4 

17 

18 
18 
18 



16 

12 

16 

12 

9 



11 
9 



8>^ 



1 



18 

10 

11 
16 



19 



11 



17 
17 



19 
18 



Remarks. 



High pressure. 



High pressure. 
Multiple no*^ 
known." 



High pressure. 



Multiple not 
known. 



Multiple not 
known. 



Multiple not 

known. 
Not tried. 



Fitted with a 
screw of an in- 
creasing pitch 



360 



LIST OF SCEEW STEAMEES. 



Name of Ship. 



Sanspariel 

Satellite 

Scout 

Seylla 

Seahorse 

Serpeut 

Severn 

Shannon 

Sharpshooter.., 



-"Minoom 

Slaney 

Snake 

Snipe 

Sparrow 

Sparrowhawk . 

Star 

Steady 

St. George 

St. Jean d'Arc. 

Supply 

Surprise 

Sutlej 

Swallow 

Tarter 

Tarte 

Teazer 

Termagant 

Terror 

Thunder 

Thunderbolt ... 
Topaze 



Torch 

Trafalgar 

Tribune 

Trusty 

Undaunted 

Urgent 

Victor 

Victor Emman- 
uel 

Victoria 



Vigilant... 

Viper 

Vulcan 

Wanderer 
Warrior.... 



Waterloo 

Windsor Castle 

Wolverine 

Wrangler 

Wye 

Zealous 

Zebra 



200 
1250 
100 
500 
500 



200 



Maker of Engines. 



Boulton and Watt. 
Penn and Son. 

Ditto. 

Ditto. 

Ditto. 
Napier. 

Maudslay and Field. 
Penn and Son. 
Ravenhill and Salkeld. 
Portsmouth Yard. 
Maudslay and Field. 
Penn and Son. 
Napier. 

Ditto. 
Humphrey & Tennant. 
Napier. 

Ditto. 
Ravenhill and Salkeld. 
Penn and Son. 



Ravenhill and Salkeld. 
Maudslay and Field. 
Ravenhill and Salkeld. 
Maudslay and Field. 

Ditto. 
Penn and Son. 
Portsmouth Factory. 
Napier. 
Ravenhill and Salkeld. 

Ditto. 
Maudslay and Field. 

Napier. 

Maudslay and Field. 

Ditto. 
Ravenhill and Salkeld. 

Ditto. 
Maudslay and Field. 
Ravenhill and Salkeld. 

Maudslay and Field. 
Ditto. 

Ditto. 

Ditto. 

Ditto. 

Ditto. 
Penn and Son. 
Ravenhill and Salkeld. 

pitto. 
Penn and Son. 



Maudslay and Field. 



Humphrey & Tennant. 



^ 






Screw. 1 


o . 




11 

la 






1 


1 


ft 


hj 


rt 


s 


P 


in. 


ft.in 




ft. in. 


ft. in. 


43}^ 


3 


50 


16 


16 


58 


3 3 


63 


23 6 


16 


58 


3 3 


63 


23 6 


16 


58 


3 3 


63 


23 6 


16 


30^ 


2 6 


112 


10 


12 


45 


2 


86 


16 4 


11 


66 


3 6 


50 


21 


18 


im 


3 6 


56 


25 3 


18 1 


46 


3 6 


38 


9 11 


8 10 


62K 


2 6 


55 


20 7 


16 


18 


1 6 




8 


6 6 


351^ 


1 8 


112 


10 


11 


32 


1 6 


106 


11 4 


9 


32 


1 6 


106 


11 4 


9 


421^ 


2 2 


92 


14 3 


11 


45 


2 


86 


16 6 


11 


32 


1 6 


106 


11 4 


9 


71 


3 


50 


20 


18 


701^ 


3 6 


61 


21 8 


18 


45 


2"'"0 


88 


16 


ir'o 


66 


3 6 


50 


21 


18 


251/ 


1 9 


80 


10 10 


9 


51 


2 3 


65 


16 6 


12 


64 


3 


50 


22 6 


17 


27 


2 6 


51 


7 


5 


62)^ 


3 6 


55 


20 


16 


25)^ 


2 


138 


14 


6 21^ 


32^^ 


2 


108 


12 


8 


76 


3 6 


45 


25 to 

28 6 


19 4 


32 


1 6 


106 


11 4 


9 


66 


3 6 


50 


21 


18 


55 


2 6 


67 


17 7 


14 1 


25M 


2 


108 


14 


6 


76 


3 6 


45 


26 


18 


64 


3 


59 


22 4 


17 


55 


2 6 


82 


20 6 


11 


76 


3 6 


bbV. 


26 2 


18 2 


92 


4 


45 


25 to 
30 


20 


45 


2 


84 


16 


11 


403^ 


2 


87 


14 11 


11 


64 


3 


50 


22 6 


17 


45 


2 


83 


16 


11 


10414 


4 


54 




24 6 


34 


2 9 


53 


13 6 


11 


71 


3 


50 


28 


18 


64% 


3 4 


18M 


18 6 


17 


40M 


2 


83 


15 


11 


4214 


2"'"2 




12 "0 


14"0 



High pressure. 



Multiple not 
known. 



Multiple 3-73 tol, 

ffigh pressure. 
Ditto. 
Ditto. 



High pressure. 



Fitted with a 
screw of an in- 
creasing pitch. 



Not tried. 



With one or two exceptions, the engines are " horizontal," and ooupled 
direct to the shaft. 

The length of the screw employed in the Royal Navy is generally about ^ 
of the pitch, and the angle varying from 20° to 30°. 

The steam-pressure in boilers is 20 lbs., with the exception of some few of 
the early screw ships, in which it is something less. 



LIST OF PADpLE STEAMERS. 



361 



List of Paddle Steamers in her Majesty's Navy. 



Name of Ship. 



Adder 

Advice 

African 1. 

Albau 

Alecto 

Antelope.... 

Ardent 

Argus , 

Asp 

Avon 

Bann 

Banshee 

Barracouta.. 

Basilisk 

Bee* 

Black Eagle 
Bloodhound. 

Brune 

Bulldog , 

Bustler , 

Buzzard 

Caradoc 

Centaur 

Comet 

Confiance..., 
Coroma.ndel 

Cuckoo , 

Cyclops 

Dasher 

Dee 

Devastation 
Dover ......... 

Dragon , 

Driver 

Echo 

Klfin 

Fearless 

Firebrand .. 

Firefly 

Fire Queen . 

Furious , 

^ury , 

Geyser , 

Gladiator.... 

Gorgon 

Harpy........ 

Hearty 

Hecate 

Hecla 

Hermes , 

Hydra 

Inflexible... 

Jackal 

Kite 

Leopard 

Lightning... 

Lizard 

Locust 

Lucifer 

Magicienne 
Medea 



100 
100 

90 
100 
200 
260 
200 
300 

50 
160 

80 
350 
300 
400 

10 
260 
150 

80 
500 
100 
300 
350 
540 

80 
100 
150 
100 
320 
100 
220 
400 

90 
560 
280 
140 

40 

76 
410 
220 
120 
400 
515 
280 
430 
320 
200 
100 
240 
240 
220 
220 
378 
150 
170 
560 
100 
150 
100 
180 
400 
350 



Maker of Engine. 



Boulton and Watt. 

Ditto. 
Maudslay and Field. 
Boulton and Watt. 
Seaward and Capel. 
Penn and Son. 
Seaward and Capel. 
Penn and Son. 
Boulton and Watt. 

Ditto. 



Penn and Son. 



Ravenhill. 
Maudslay and Field. 
Penn and Son. 
Napier. 



Rennie. 



Seaward and Capel. 
Boulton and Watt. 

Ditto. 
Maudslay and Field. 



Boulton and Watt. 
Seaward and Capel. 

Ditto. 
Maudslay and Field. 

Ditto 
Fawcett. 
Fairbairn. 
Seaward and Capel. 
Maudslay and Field. 
Rennie. 

Boulton and Watt. 
Seaward and Capel. 
Maudslay and Field. 
Napier. 
Ravenhill. 
Rigby. 
Seaward. 
Ravenhill. 
Seaward. 
Napier. 



Scott and Sinclair. 

Ditto. 
Maudslay and Field. 
Boulton and Watt. 
Fawcett. 
Napier. 



Seaward and Capel., 
Maudslay and Field. 
Napier. 
Maudslay and Field. 

Ditto. 
Penn and Son. 
Maudslay and Field. 









II 


5^ 


II 


£ >i 


M^ 




go 


gM 


%^ 


fi 




« ft 


in. 


ft. in. 




39U 


3 6 


29 , 


39g 


3 6 


27 


35k 
39k 
Ooya 


3 6 


27 


3 6 

4 6 


28 
14 


64 


4 6 


26 


53 


4 6 


1814 


64 


6 


16^^ 




2 6 


33 


48J^ 


4 6 


16 


72^ 


5 




74 


6 




20 


2 


40 






5 6 


16 


64 


6"o 


... 


75 


4 4 


24 


851^ 


6 


18 


35g 


3 6 


28 


40 


4 


23 


39^ 


3"6 


27 


64 


5 6 


16 


403^ 


3 4 


28 


54 


5 


18 


54 


6 


18 


38 


S 


28 


88 


5 9 


17 


62 


5 4 


19 


443^ 


4 6 


18 


27 


2 6 




353^ 


3 2 


32 


75>^ 


5 9 


18 


551^ 


5 


21 


60 


3 9 


31 


72 


7 


16 


84 


5 9 


21 


63 


5 3 


18 


n% 


5 9 


22 


64 


5 6 


18 


49 


4 


23 


60 


5"9 


1& 


60 


5 9 


18 


40 


4 6 


19 


56 


5 


17 


72 


5 9 




48 


4 


21 


47 i^ 
91k 


4 3 


22 


6 8 


17 


40 


4 


25 


48 


4 


22 


40 


3 6 


27 


48 


4 6 




72 


7 




50 


5 8 


... 






ft. in. 
14 
14 
14 
14 
21 11 
20 
20 9 
23 5 
10 



28 

13 6 

14 

14" "e 

26 
16 



18 6 

11 4 

12 

26 6 
20 
16 3 

27 4 

25 6 

26 6 
26 
26 
16 



18 



* Paddle and Screw. 



362 



LIST OF PAODLE STEAMERS. 



Name of Ship. 



Medina 

Medusa 

Merlin 

Monkey 

Myrmidon 

Myrtle 

Oberon 

Odin 

Osborne 

Otter 

Penelope 

Pigmy 

Pike 

Pluto 

Porcupine , 

Princess Alice 

Prometheus 

Prospero 

Recruit 

Redpole 

Retribution , 

Rbadamanthus 

Rosamond , 

Salamander , 

Sampson , 

Scourge 

Sidon 1 

Sphynx 

Spiteful 

Spitfire , 

Sprightly 

Stromboli 

Styx 

Tartarus , 

Terrible 

Thalis 

Torch 

Trident 

Triton 

Valorous 

Vesuvius 

Victoria and Albert, 

Virago 

Vivid 

Vixen 

Volcano 

Vulture 

Wallace 

Weser 

Widgeon 

Wildfire 

Zephyr 



312 
312 
312 
130 
150 

50 
260 
560 
430 
120 
650 
100 

50 
100 
132 
120 
200 
144 
160 
160 
400 
220 
280 
220 
467 
420 
560 
500 
280 
140 
100 
280 
280 
136 
800 

80 
150 
350 



280 
600 

Soo 

160 
280 
140 
470 
100 
160 
90 
76 
100 



Maker of Engine. 



Fawcett. 

Ditto. 

Ditto. 
Boulton and Watt. 

Ditto. 

Ditto. 
Rennie. 
Fairbairn. 

Maudslay and Field. 
Boulton and Watt. 
Seaward and Capel. 
Fawcett. 



Boulton and Watt. 
Maudslay and Field. 

Ditto. 
Seaward. 



Penn and Son. 

Maudslay and Field. 

Ravenhill. 

Maudslay and Field. 

Rennie. 

Maudslay and Field. 

Seaward. 

Penn and Son. 

Scott and Sinclair. 

Butterly Company. 

Boulton and Watt. 

Napier. 

Seaward. 

Boulton and Watt. 

Maudslay and Field. 



Seaward and Capel. 

Ditto. 
Boulton and Watt. 
Ponn and Son. 
Napier. 
Penn and Son. 
Boulton and Watt. 
Penn and Son. 
Seaward -and Capel. 

Ditto. 
Fairbairn. 



Boulton and Watt. 



in. 
64 
64 
64 

S^ 

30 
61 

881^ 

54 

44^ 

35 

301^ 
u2 



72 

55> 

65' 

54 



821^ 

62 

441^ 

391^ 

63 



72 



661^ 

63 
45 
80% 



351^ 
39k 



ft. in. 

6 

6 

6 

3 6 
2 6 

4 

5 

6 9 
6 



7 
5 
5 
5 

5 8 

6 
6 
6 
6 

4 6 
3 6 
6 

5 3 
3 6 

8 



11 

II 



ft. in 

24 e 

24 e 

24 e 

14 C 

17 C 

19 £ 

21 C 

27 e 

32 



14 





82 





10 





14 





15 


6 


22 


6 


14 


9 



25 

20 
23 4 

21 

27 6 

28 
27 6 



25 



26 6 



13 9 
12 

14 



The steam-pressure in the paddle steam-ship's boilers varies from 
8 lbs. to 16 lbs. ; some few are working at 20 lbs. 

Most of the paddle-steamers have common paddle-wheels. Her 
Majesty's yacht "Victoria and Albert," and a few other vessels, have 
the "feathering wheel," — that known as "Morgan's wheel.' 



LIST OF STEAM GUA'-BOATS. 



363 



List of Steam Gun-boats (High Pressure) in the 
Boyal Navy.^ 



Horse- 
power, 

Albacore 60 

Amelia 60 

Angler 20 

Ant 20 

Badger 60 

Banterer 60 

Beaver.. 60 

Beacon 60 

Biter 60 

Blazer 60 

Blossom 20 

Bouncer 60 

Boxer 60 

Brave 60 

Brazen 60 

Bullfinch 60 

Bullfrog 60 

Bustard 60 

Camel 60 

Carnation 60 

Caroline 60 

Charger 60 

Charon •. 60 

Cheerful 20 

Cherokee 60 

Chub 20 

Clinker 60 

Clown 40 

Cochin 60 

Cockchafer 60 

Confounder 60 

Cracker. 60 

Crocus * . . . . 60 

Daisy 20 



Horse- 
power. 

Dapper 60 

Delight 60 

Decoy 20 

Dove 60 

Drake 40 

Dwarf 20 

Earnest 60 

Erne 60 

Escort 60 

Fancy 60 

Fenella 40 

Fervent 60 

Fidget 20 

Firm 60 

Flamer 60 

Flirt 20 

Fly 60 

Foam 60 

Forester 60 

Forward ,60 

Gadfly 20 

Garland 20 

Garnet 40 

Gleaner 60 

Gnat 20 

Goldfinch 60 

Goshawk 60 

Grappler 60 

Grasshopper 60 

Grinder 60 

Griper 60 

Growler 60 

Handy 40 

Hardy 60 



* Most of the gua-boats are fitted by Maudslay and Penu with engines of the locomo- 
tive and trunk kind coupled direct to the screw-shaft. 

Diameter of cylinder (60 horse power) 16^ in. . . Maudslay. 
" " (60 " ) 21 in. Trtink 11 in. Pena 

(40 " )21iii. 

' " " (20 » )15in. . . ♦« 



LIST OF STEAM GUN-BOATS. 



Horse- 
power. 

Hasty 60 

Haughty 60 

Havock 60 

Herring 60 

Highlander 60 

Hind 60 

Hunter 40 

Hyaena 60 

Insolent 60 

Jackdaw 60 

Janus 40 

Julia 60 

Kestrel 40 

Lark 60 

Leveret 60 

Lively 60 

Louisa 60 

Mackerel 60 

Magnet 60 

Magpie 60 

Manly 60 

Mastiff 60 

Mayflower 60 

Midge ; 20 

Mistletoe 60 

Nettle 20 

Nightingale 60 

Onyx 20 

Opossiim 60 

Parthian 60 

Partridge 60 

Peacock 60 

Pelter 60 

Pest 20 

Pet 20 

Pheasant 60 

Pickle 60 

Pincher , 60 

Plover 60 

PoBpoise 60 

Primrose 60 

Procris 60 

Prompt 60 

Quail 60 



Horse- 
power. 
Eainbow 60 

Eambler 20 

Eaven 60 

Eeady 40 

Eedbreast 60 

Eedwing 60 

Eipple 60 

Eocket 60 

Eose 60 

Euby 60 

Sandfly 60 

Savage . . .- 60 

Seagull 60 

Sepoy 60 

Shamrock 60 

Sheldrake 60 

Shipjack 60 

Skylark 60 

Snap 60 

Snapper 60 

Spanker 60 

Spey 60 

Spider 60 

Starhng 60 

Staunch 60 

Stork 60 

Surly 60 

Swan 60 

Swinger 60 

Thistle 60 

Thrasher 60 

Thrush 60 

Tickler 60 

Tilbury 60 

Tiny , .... 60 

Traveller 60 

Yiolet ...\ 60 

Watchful 40 

Wave • 60 

Weazel 60 

Whiting 60 

Wolf 60 

Woodcock 40 



ALPHABETICAL INDEX. 



74. Air-pump. 

' I double-acting. 

19LJ ^ 

367. amount of power consumed by. 

118. bucket, annular. 

329. Angle of screw, to find. 

342. of crank, for given positioAS of the piston. 

355. Area of a circle. 

362. of an ellipse. 

■ i of a screw-blade. 

333.1 

' [■ Ash-pits of boilers. 

225. to be kept clear of ashes. 

234. Ashes escaping from funnel 

111. Back-Balance 

215. Back-lash. 

214. Banking up. 

151. Barometer-gauge. 

249. Bearings of engines, duties to. 

250. soft metal for. 

278. to be examined. 

279. outer, of paddle-shafts. 

158. Bilge-pumps. 

267. to clear the bilge. 

73. Blast-pipe. 

99. 
107. 

99. Blowing through. 

319. process of, when no blow-valve is fitted. 

320. delayed by cold. 

90. Blow-out cocks. 

■ \ when closed, to ascertain. 

365 



* I Blow-valve. 



S66 INDEX. 

Aet. 

229. Blow-out cocks, if set fast. 
222. Blowing out when under steam. 
274. in harbor. 

231. to be limited at times. 

230. Blowing off steam when vessel is pitching. 
40. Boiling-point. 

49. of fresh water. 

50. of salt water, v 

64. Boilers (marine). 

65. gear connected with. 

66. tubular. 

71. ' for gun-boats. * 

196. height of water on lighting fires. 

220. duties to, when steaming. 

237. water low in. 

194. method of filKng. 

228. method of feeding. 

232. numbej: to be used at one time. 

263. temporary repairs to. 

291. on cleaning out and scaling. 

293. on stopping cracks in. 

295. on staying the. 

309. on preserving, when not in use. 

84. Boiled water-gauge. 

221. duties to, when steaming. 

297. water unsteady in. 

75. hand-pumps. 

183. Boulton and Watt's marine engines. 

91. Brine pumps and valves. 

3. Caloric, definition of. 

29. unit of. 

33. Calorimeter. 

28. Capacity for heat. 

361. Circular inch. 

354. Circumference of circle. 

363. '■ of ellipse. 

109. Clearance. 

:349. Coal, weight of. 

351. effects of stowage upon. 

352. decay of. 

353. Coal, quaUties of. 

302. bunkers to he examined. 

303. Coaling ship. 



INDEX. 867 



ART. 

213. Cold surfaces, chilling effects of. 

36. Combustion. 

37. temperature necessary for. 

89. Communication-valves. 

209. danger of opening them if all the boilers 

are not in use. 

99. Condenser. 

151. gauge. 

347. temperature of. 

245. if leaky. 

19. Conduction. 

20. Conducting power of substances. 
360. Cone, volume of. 

365. (frustum) volume of. ^ ' 

338. Consumption of fuel in a given time. 
339. in a given distance. 

22. Convection, law of. 

23. advantages to be derived from a knowledge of. 

24. explanation of natural phenomena by means 

of. 

18. Cooling of hot bodies, law of. 
145. Cornish valve. 

342. Crank, on the motion of. .« 

110 I Cross-head to cylinder and air-pump. 

I Cross-tail. 
130. Cushioning, meaning of. 
356. Cylinder, surface of. 

357. volume of. 

273. cover, method of w^orking without. 

314. > — to raise by tackles. 

^^^' \ D-slide, the long. 

125. i ' ^ 

126. the short. 

87. Dampers. 

247. attention to. 

201. Danger arising from solid substances under the moving parts 
of an engine. 

65. Dead-plates of boilers. 

99.| 
106. > Delivery-valve. 
121. i 
119. (annular). 

44. Dew, formation of. 
24 



o63 INDEX. 

AKT. 

45. Dew, formation of, causes of. 

178. Direct-acting marine paddle-engines. 

]8T. . ^ screw-engines. 

123. Disch-arge-valve. 

52. Distillation, process of. 

74. Donkey engine. 

191. Double-acting air-pump. 

182. Double-cylinder engines. 

140. Double eccentric. 

236. Draught of air to the fires. 

80. Drip-pipe. 

323. Duty of an engine. 

136. Eccentric, description of. 
140. . double. 

137. — throw of. 

138. pulley (placing the stops on). 

289. rod, to adjust the. 

322. Efficiency of engines, measure of. 

362. Ellipse, area of. 

363. circumference of 

199. Engines, duty to, while steam is forming. 

201. when ready for starting. 

205. — ^ how to commence steaming with only one in gear, 

20G. to he moved before leaving the moorings. 

241. worked on high-pressure principle. 

243. leaks in. 

265. method of working with only one. 

276. duties to, on arriving at port. 

146. Equilibrium-valve. 

113. Escape-valves of cylinder. 

72. Exhaust-pipe. 

7. Expansion from heat, rate of. 

8. ■■ of gases. 

9. '— practical mode of observing, 

■ 10. various applications of this principle. 

11. Expansion from heat, law of, not universal. 

12. benefits arising from a deviation in the 

general law. ■ 

13. to show that the general law is not 

universal. 

142. Expansion-valve, description of. 

156.- Expansion cams and gear. 

251. Expansive working, remarks on. 



INDEX. 309 



181. Fairbairn's engips. 

157. Feed-pumps. 

246. attention to. 

257. Fire, precautions against, during an action. 
197. Fires, method of laying. 

214, to bank up. 

215. to put back. 

227. management of. 

'236. supply of air to. 

258. : management of, during an action.. 

275. hauling out. 

300. Fire-bars, replacing. 
66. box. 

I bridges of boilers. 

69. i ^ 

.294* repairing the. 

99. -j 

106. I Foot-valve. 

117. J 

III}- ^^^'^^'^- 

17. Freezing-point. 
348. Fuel, on the qualities of. 

253. management of, while steaming. 

346. lost by blowing out. 

234. Funnel, ashes, etc., escaping from. 

235. flame appearing at the top of. 

260. effect of shot upon. 

301. on sweeping the. 

no. Gab-levers. 

39. Galvanic action, effects of. 

83. Gauge-cocks. 

255. Gear for repairing damages. 

179. Gorgon engines, description of. 

180. length of radius-rod. 

177. Governors £tted to screw-vessels. 

148. Gridiron-valve. 

75. Hand-pumps. 

276. Harbor, duties to engines on arriving in. 

5. Heat and cold, definition of. 

6. general effects of 

34. sources of. 

53. High-pressure steam. 



370^ IXDEX. 



ART. 



281. Holding-down bolts, screwing-down. 

144. Hornblower's valve. 

324. Horse-power of an engine. 

326. from the evaporation of the boiler. 

193. Humphrey's horizontal engine. 

106. Hot-well. 

361. Inch, circular and square. 

106. Injection-cock. 

200. orifice, if choked up. 

106. pipe. 

239. duties to. 

242. Injecting from the bilge. 

160. Intermediate shaft. 

106. Jackets of cylinders. 

218. attention required to. 

85. Kingston's valves. 

240. duties to. 

27. Land and sea breezes. 

132. Lap on slides. 

133. effect of. 

30. Latent heat. 

131. Lead of slides. 

341 . Locomotive performance of marine engines. 

155. Lubricators. 

277. to be examined. 

256. Machinery to be examined before an action. 

184. Miller, and Ravenhill's marine engines. 

310. Mud-hole doors, how to be fitted. 

98. Newcomen's engine. 

325. Nominal horse-power. 

i Oscillating engines. 

38. Oxidation, 

160. Paddle-wheels. 

166. brakes of. 

163.- modes of disconnecting. 

259. Paddle-wheels, casualties to, in an action. 

312. method of turning, by hand. 

162. Paddle-boards, reefing of. 

165. ■ ^ — immersion of. 

161. feathering, 

286. Paddle-shafts to adjust. 

337. Paddle-steamers, speed of, in still water. 



185. 
189. 



INDEX. 871 

ART. 

^^"'- !■ Parallel motion. 
114. J 

284. — ■ to adjust. 

350. Patent fuels. 

147. Penelope (H.M.S.), valves of. 

109. Piston of steam-cylinder. 

272. Piston-rod, to straighten. 

280. Piston-glands, etc. 

316. Piston, to escertain whether it be steam-tight. 

317, loose on the rod. 

i pitch of screw, to find. 
332. F 

334. Power exerted by a screw-propeller. 

254. Preparatory orders before stopping engines. 

230. Pressure of boiler varies as ship rolls. 

211. Priming, while getting up steam. 
210. ■ causes of, on first starting. 

212. remedies against. 

15. Pyrometer, description of. 

159. Propulsion, modes of. 

25. Radiation. 

26. Radiating power of the bodies. 
114. -j 

285. V Radius-bar. 
344. J 

340. Reefing-paddles, remarks on. 

91. Refrigerators. 

192. Return connecting-rod engine (Mau(islay and Field). 

88. Reverse-valve. 

292. Rust-joints. 

76. Safety-valve. 

78. on increasing the load upon. 

216. when banking up. 

79. Safety-valve box. 

224. SaUnometer. 

223. Saturation of water in boilers, to prevent. 

224. . limits of. 

167. Screw-propeller. 

328. investigations connected with. 

168. length of. 

169. angle of. 

170. pitch of. 

171. ^ slip of. 



372 INDEX. 

ART. 

172. Screw-propeller, area of. 

173. thread of. 

174. diameter of. 

175. method of disconnecting, 

176. modes of raising. 

266. remarks on. 

306. Screw-gearing to be examined. 

307. to be lubricated. 

186. engines for. 

313. on tm-ning, by hand. 

321. attention to. 

61. Sea-water, analysis of. 

128. Seward's shdes. 
110. ^ Side-levers. 

106. Side-lever engines, working parts of. 

[ Slides, method of working. 
136. J ° 

244. leaks in. 

124. various kinds of. 

125. longD. ■ 

126. short D. 

127. locomotive. 

128. Seward's. 

129. cylindrical. 

139. travel of. 

282. examining, repacking, etc. 

287. to set. ■ 

290. remarks on the alteration of. 

290. Shde-rods, to adjust. 

335. Slip of a screw. 

123. Sluice-valve. 

67. Smoke-box of boilers. 

250. Soft metal for bearings. * 

3^6. Speed, the most economical in a tide-way. 

204. Starting the engineg. 

205. with one engine in gear. 

207. from moorings before the steam is well up. 

1. Steam, definition of. 
47. method of obtaining. 



^^- 1 laws of. 

57. i , 

51. from salt-water. 

53. high-pressure. 



IXDEX. H73 



ART. 



♦ 54. Steam, measured by atmospheres. 

55. in contact with the water of a boiler 

42. temperature of, 

58. specific gravity of. 

59. common. 

60. super-heated. 

198. to get up with despatch. 

262. how to be regulated during an action. 

274. blowing off. 

311. to be got up occasionally. 

95. Steam-engine, definition of. 

98. » Newcomen's. 

100. single-acting. 

102. double-acting. 

104. non-condensittj?^ 

105. '■ marine. 

270. Steamers in chase. 

68. Steam-chest. 

252. Steam-circle. 

81 1 

■ [ Steam-gauges. 
82.] "" ° 

299. Steam-gauges to be esramined in harbor. 

217. of strange boilers. 

208. Steaming through a difficult passage. 

264. Steam-pipe, etc., to be repaired temporarily. 

226\ Stoking, remarks on. 

112. Strap, gib, and cutter. 

283. Stroke of an engine. 

233. Superheating apparatus. 

234. Surface of a cylinder, to find. 
92. Surface blow-out pipe. 

115. condensation. 

4. Temperature, definition of. 

14. • method of ascertaining. 

21. the sensations not a good indication of. 

42. of gaseous fluids. 

347. ■ for condenser. 

116. Test-cocks and grease-cocks. 

16. Thermometer, mercurial, description of. 

17. Thermometers, to compare, when difftu-ently graduated. 
141. Throttle-valve, description of. * 
199. . whether open or shut, to discover. 

143. used as expansioii-s';i";ve. 



374 INDEX. 



ART. 



190. Trunk-engines. 

269. Tubes of boilers, to repair temporarily. 

111. Yalve-lifter. 

43. Vapor. 

46. "Vapor and steam, -distinction between. 

357. Volume of a cylinder, to find. 

359. of a sphere. 

260. of a cone, to find 

365. of a frustum of a cone, to find. 

2. Water, definition of. 

86. Wash-plates. 

106. Waste-water pipe. 

80, Waste-steam funnel. 

99. Watt, discoveries of. 

366." Weight of any body, to fina. 

111. Weigh-shaft. 

343. Work developed by the crank. 



PJLATE JI 




practical aniSamtifit§0flks, 

PUBLISHED BY 

HENRY CAREY BAIRD, 

INDUSTRIAL PUBLISHER, 

PHILADELPHIA. 



t^ Any of the following Books will be sent by mail, free 
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Affiericaii Miller and Millwright's Assistant: 

A new and thorouglily revised ^Edition, with additional 
Engravings. By William Carter Hughes. In one vol- 
ume, 12 mo., .• $1.25 

Ariiieugaiid, Amoroux,.aiid Johnson. 

r THE PRACTICAL DRAUGHTSMAN'S BOOK OF INDUS- 
TRIAL DESIGN, and Machinist's and Engineer's Drawing 
Companion ; forming a complete course of Mechanical 
Engineering and Architectural Drawing. From the French 
of M. Armengaud the elder. Prof, of Design in the Con- 
servatoire of Arts and Industry, Paris, and MM. Armen- 
gaud the younger, and Amouroux, Civil Engineers. Re- 
written and arranged, with additional matter and plates, 
selections from and examples of the most useful and 
generally employed mechanism of the day. By William 
Johnson, Assoc. Inst. C. E., Editor of "The Practical 
Mechanic's Journal." « Illustrated by fifty folio steel 
plates and fifty wood-cuts. A new edition, 4to.,... $10.00 

Among. the contents are '.—Linear Drawing, Befinitions and Problems, 
PSate I. Applications, Designs for inlaid Pavements, Ceilings and 
Balconies, Plate II. Sweeps, Sections and Mouldings, Plate III. Ele 
mentary Gothic Forms and Rosettea, Plate IV. Ovals, Ellipses, 

1 



PHACTICAL AND SCIENTIFIC BOOKS, 



Parabolas and Volutes, Plate V. Rules and Practical Data. Study o* 
Projcctiovs, Elementarj^ Principles, Plate VI. Of Prisms and other 
Solids, Plate VII. Rules and Practical Data. On Coloring Sections, with 
Applications — Conventional Colors, Composition or Mixture of Colors, 
Plate X. Continuation of the Study of Projections— Vse of sections— de- 
tails of machinery, Plate XI. Simple applications— spindles, shafts, 
couplings, wooden patterns, Plate XII. Method of constructing a 
wooden model or pattern of a coupling. Elementary applications- 
rails and chairs for railways, Plate XIII. Rules and Practical Data — 
Strength of material, Resistance to compression or crushing force, 
Tensional Resistance, Resistance to flexure, Resistance to torsion, 
Friction of surfaces in contact. 

The Intersection and Development of Surfaces, with Ap- 
plications. — The Intersection of Cylinders and Cones, Plate XIV. The 
Delineation and Development of Helices, Screivs &nd Serpentines, Plata 

XV. Application of the helix — the construction of a staircase, Plate 

XVI. The Intersection of surfaces — applications to stop-cocks, Plate 

XVII. Rules and Practical Data — Steam, Unity of heat. Heating surface, 
Calculation of the dimensions of boilers, Dimensions of firegrates, 
Chimneys, Safety-valves. 

The Study and Construction of Toothed Gear.— Involute, cy- 
cloid, and epicycloid, Plates XVIII. and XIX. Involute, Fig. 1, Plate 

XVIII. Cycloid, Fig. 2, Plate XVIII. External epicycloid, described 
by a circle rolling about a fixed circle inside it. Fig. 3, Plate XIX. 
Internal epicycloid, Fig. 2, Plate XIX. Delineation of a rack and 
pinion in gear. Fig. 4, Plate XVIII. Gearing of a worm with a worm- 
wheel. Figs. 5 and 6, Plate XVIII. Cylindrical or Spur Gearing, Plate 

XIX. Practical delineation of a couple of Spur-wheels, Plate XX. 
The Delineation and Construction of Wooden Patterns for Toothed Wheels, 
Plate XXI. Rules and Practical Datd. — Toothed gearing, Angular and 
circumferential velocity of wheels. Dimensions of gearing. Thickness 
of the teeth. Pitch of the teeth, Dimensions of the web, Number and 
dimensions of the arms, wooden patterns. 

Continuation of the Sttz-dy of Toothed Gear.— Design for a 
pair of bevel-wheels in geaf, Plate XXII. Construction "of wooden 
patterns for a pair of bevel-wheels, Plate XXIII. Involute and 
Helical Teeth, Plate XXIV. Contrivances for obtaining Differential 
Movements— The delineation of eccentrics and cams, Plate XXV. Rules 
a-ud Practical Dato— Mechanical work of effect. The simple machines. 
Centre of gravity, On estimating the power of prime movers. Calcu- 
lation for the brake. The fall of bodies. Momentum, Central forces. 

Elementary Principles of Shadows. — Shadows of Prisms, Pyra^' 
mids and Cylinders, Plate XXVI. Principles of Shading, Plate XXVII. 
Continuation of the Study of Shadows, Plate XXVIII. Tuscan Orde>; 
Plate XXIX. Rules and Practical Data — Pumps, Hydrostatic principles. 
Forcing pumps. Lifting and forcing pumps. The Hydrostatic press, 
Hydrostatical calculations and data — discharge of Avater through dif- 
ferent orifices. Gaging of a water-course of uniform section and fall. 
Velocity of the bottom of water-courses. Calculation of the discharge 
of water through rectangular orifices of narrow edges. Calculation of 
the discharge of water through overshot outlets. To determine the 
width of an overshot outlet. To determine the depth of the outlet. 
Outlet with a spout or duct. 

Application of Shadows to Toothed Gear, Plate XXX. Ap- 
plication of Shadows to Screws, Plate XXXI. Aj)plication of Shadows to 
a Boiler and its Furnace, Plate XXXII. Shading in Black— Shading in 
Colors, Plate XXXIII. 

The Cutting and Shaping of Masonry, Plate XXXIV. Rxdes 
and Practical i)ato— Hydraulic motors, Undershot water wheels, witli 
plane floats and a circular channel. Width, Diameter, Velocity, Num- 
ber and capacity of the buckets. Useful efTect of the water wheel. 
Overshot water wheels. Water wheels with radial floats. Water wheel 
with curved buckets. Turbines. Remarks on Machine Tools. 
2 



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Design for a water wheel, Sketch of a water wheel ; Overshot Water 
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expansive steam engine, Plates XXXVIII., XXXIX. and XL. Details 
of Construction ; Movements of the Distribution and Expansion Valves ; 
Rules and Practical Z>a^a— Steam engines : Low-pressure condensing 
engines without expansion valve. Diameter of piston, Velocities, 
Steam pipes and passages. Air-pump and condenser. Cold-water and 
feed-pumps, High-pressure expansive engines, Medium pressure con- 
densing and expansive steam engine, Conical pendulum or centrifugal 
governor. 

Oblique Projections. — Application of rules to the delineation of 
an oscillating cylinder, Plate XLI. 

Parallel Perspective. — Principles and applications, Plate XLII. 

True Perspective.— Elementary principles, Plate XLIII. Appli- 
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Derived from Coal Tar; 

Their Practical Application in Dyeing Cotton, Wool, and 



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Paris — Futschine, or Magenta — Coloring Matters obtained by other 
bases from Coal Tar — Nitroso-Phenyline — Di Nitro-Aniline — Nitro- 
Phenyline — Picric Acid — Rosolic Acid — Quin'oline — Napthaline Colors 
— Chloroxynaphthalic and Perchloroxynapthalic Acids— Carminaph- 
tha — Ninaphthalamine — Nitrosonaphthaline — Naphthamein — Tar Red 
— Azuline — Application of Coal Tar Colors to the Art of Dyeing and 
Calico Printing — Action of Light on Coloring Matters from Coal Tar 
— Latest Improvements in the Art of Dyeing— Chrysammic Acid— Mo- 
lybdic and Picric Acids— Extract of Madder— Theory of the Fixation 
of Coloring Matters in Dyeing and Printing— Principles of the Action 
of the most important Mordants — Aluminous Mordants — Ferruginous 
Mordants — Stanniferous Mordants — Artificial Alizarin — Metallic Hy- 
posulphites as Mordants — Dyer's Soap — Preparation of Indigo for Dye- 
ing and Printing— Relative Value of Indigo— Chinese Green Murexide. 

Dyer and Color-maker's Companion; 

Containing upwards of two hundred Receipts for making 
Colors, on the most approved principles, for all the 
various styles and fabrics now in existence ; with the 
Scouring Process, and plain Directions for Preparing, 
Washing-off, and Finishing the Goods. Second edition. 
In one volume, 12mo $1.25 



French Dyer, (The; 



Comprising the Art of Dyeing in Woolen, Silk, Cotton, 
etc., etc. By M. M. Riffault, Vernaud, De Fonteuelle, 
Thillaye, and Mallepeyre. (^In press.) 

Loye. The Art of Dyeing, Cleaning, Scorning, 
and Finishing, 

On the Most Approved English and French Methods ; 
being Practical Instructions in Dyeing Silks, Woolens 
and Cottons, Feathers, Chips, Straw, etc.. Scouring and 
Cleaning Bed and Window Curtains, Carpets, Rugs, etc., 
French and English Cleaning, any Color or Fabric of 
Silk, Satin, or Damask. By Thomas Love, a working 

Dyer and Scourer. In one volume, 12mo ....$3.00 

9 



PEACTICAIi A]!srD SCIENTIFIC BOOKS, 

O'J^eill. Chemistry of Calico Printing, Dye- 
ing, and Bleacliing ; 

Including Silken, Woolen, and Mixed Goods ; Practical 
and Theoretical. By Charles O'Neill. (In press.) 

O'Neill. A Dictionary of Calico Printing and 
Dyeing. 

By Charles O'Neill. (^In press.) 

Scott. Tlie Practical Cotton-spinner and Man- 
nfacturer ; 

Or, The Manager and Overlooker's Companion. This 
work contains a Comprehensive System of Calculations 
for Mill Grearing and Machinery, from the first Moving 
Power, through the different processes of Carding, Draw- 
ing, Slabbing, Roving, Spinning, and Weaving, adapted 
to American Machinery, Practice and Usages. Compen- 
dious Tables of Yarns and Reeds are added. Illustrated 
by large Working-Drawings of the most approved Ameri- 
can Cotton Machinery. Complete in one volume, oc- 
tavo $5.00 

This edition of Scott's Cotton-Spinner, by Oliver Byrne, is designed 
for the American Operative; It will be found intensely practical, and 
will be of the greatest possible value to the Manager. Overseer, and 
Workman. 

Sellers. The Color-mixer. 

By John Sellers, an Experienced Practical Workman. 
To which is added a Catechism of Chemistry. In one 
volume, 12mo $2.50 

Smith. The Dyer's Instrnctor; 

Comprising Practical Instructions in the Art of Dyeing 
Silk, Cotton, Wool and Worsted, and Woolen Goods, as 
Single and Two-colored Damasks, Moreens, Camlets, 
Lastings, Shot Cobourgs, Silk Striped Orleans, Plain Or- 
leans, from White and Colored Warps, Merinos, Woolens, 
Yarns, etc.; containing nearly eight hundred Receipts. 
To which is added a Treatise on the Art of Padding, and 
the Printing of Silk Warps, Skeins and Handkerchiefs, 
and the various Mordants and Colors for the different 
10 



PUBLISHED BY HEKRY C iLREY BAIRD. 



Styles of such work. By David Smitli, Pattern Dyer. 
A neTV edition, in one volume, 12nio $3.00 

COI^TENTS.— Wool Dyeing, 60 receipts— Cotton Dyeing, 68 re- 
ceipts — Silk Dyeing, 60 receipts — Woolen Yarn Dyeing, 59 receipts — 
Worsted Yarn Dyeing, 61 receipts — Woolen Dyeing, 52 receipts — Da- 
mask Dyeing, 40 receipts— Moreen Dyeing, 33 receipts— Two-Colored 
Damask Dyeing, 21 receipts — Camlet Dyeing, 23 receipts— Lasting Dye- 
ing, 23 receipts— Shot Cobourg Dyeing, 18 receipts— Silk Striped Or- 
leans, from Black, White, and Colored Warps, 23 receipts — Colored 
Orleans, from Black Warps, 15 receipts — ColoTed Orleans and Co- 
bo urgs, from White Warps, 27 receipts — Colored Merinos, 41 receipts 
—Woolen Shawl Dyeing, 15 receipts— Padding, 42 receipts— Silk Warp, 
Skein, and Handkerchief Printing, 62 receipts— Nature and Use of Dye- 
wares, including Alum, Annotta, Archil, Ammonia, Argol, Super 
Argol, Camwood, Catechu, Cochineal, Chrome, or Bichromate of Pot- 
ash, Cudbear, Chemic, or Sulphate of Indigo, French Berry, or Persian 
Berry, Fustic or Young Fustic, Galls, Indigo, Kermes or Lac Dye, 
Logwood, Madder, Nitric Acid or Aqua Fortis, Nitrates, Oxalic Tin. 
Peachwood, Prussiate of Potash, Quercitron Bark, Safflower, Saun- 
ders or Red Sandal, Sapan Wood, Sumach, Turmeric, Examination of 
Water by Tests, etc., etc. 



[Jlricli. Diissaiice, A Complete Treatise 

Ox THE Aet of Dyeing Cotton and Wool, as practised m 
Pakis, Rouen, Mulhouse and Geemant. From tlie French 
of M. Louis Ulrich, a Practical Dyer in tlie principal 
Manufactories of Paris, Rouen, Mulhouse, etc., etc. ; to 
which are added the most important Receipts for Dyeing 
Wool, as practised in the Manufacture Imperiale des 
Gohelins, Paris. By Professor H. Dussauce. 12mo..$3.00 
CONTENTS.— 

Rouen Dyes, 106 Receipts. 

Alsace " 235 " 

German " 109 « 

Mulhouse " 72 " 

Parisian " 56 " 

Gobelins " 100 « 
In all nearly 700 Receipts. 



Easton. A Practical Treatise on Street or 
Horse-power Railways; 

Their Location, Construction and Management ; with 
general Plans and Rules for their Organization and Ope- 
ration ; together with Examinations as to their Compara- 

11 



PEA-CTICALi AK"D SCIENTIFIC BOOKS, 

tive Advantages over the Omnibus System, and Inquiries 
as to their Value for Investment ; including Copies of 
Municipal Ordinances relating tliereto. By Alexander 
Easton. C. E. Illustrated hy twenty-three plates, 8vo., 
cloth..! $2.00 

Exaiiiinations of Drugs, Medicines, Chemicals, 
etc., 

As to their Purity and Adulterations. By C. H. Peirce, 
M. D. 12mo., cloth ' $2.50 

Fisher's Photogenic Mampulation. 

16mo., cloth ,-. 62' 

Gas and Ventilation; 

A Practical Treatise on Gra£ ':3l Ventilation. By E. E. 
Perkins. 12mo., cloth .$1.00 

Gilhart. A Practical Treatise on Banking. 

By James William Grilbart, F. R. S. A new enlarged and 
improved edition. Edited by J. Smith Homans, editor 
of " Banker's Magazine." To which is added " Money," 
by H. C. Carey. 8vo $3.50 

Gregory's Mathematics for Practical Men; 

Adapted to the Pursuits of Surveyors, Architects, Me- 
chanics and Civil Engineers. 8vo., plates, cloth. ..$2.25 

Hardwich, A Manual of Photographic Cheui' 
istry ; 

Including the practice of the Collodion Process. By J. 
F. Hardwich. (^In press.) 

Hay. The Interior Decorator; 

The Laws of Harmonious Coloring adapted to Interior 
Decorations ; with a Practical Treatise on House Paint- 
ing. By D. R. Hay, House Painter and Decorator. Il- 
lustrated by a Diagram of the Primary, Seeondary and 
Tertiary Colors. 12mo. {In press.) 
12 



PUBLISHED BY HSJNTKY CABEY BAIRD. 

liiveiilor's Guide — Patent Office and Patent 
Laws I 

Or, a Guide to Inventors, and a Book of Reference for 
Judges, Lawyers, Magistrates, and others. By J: G. 
Moore. 12mo., cloth $1.25 

Jervis. Raiiway Property. A Treatise 

On the Constkuction and Management of Railways ; de- 
signed to afford useful knowledge, in the popular style, 
to the holders of this class of property ; as well as Rail- 
way Managers, Officers and Agents. By John B. Jervis, 
late Chief Engineer of the Hudson River Railroad, Cro- 
ton Aqueduct, etc. One volume, 12mo., cloth $2.00 

COTQ'TEiN'TS. — Preface — Introduction. Construction. — Introduc- 
tory — Land and Land Damages — Location of Line — Method of Business 
—Grading— Bridges and Culverts— Road Crossings— Ballasting Track- 
Cross Sleepers— Chairs and Spikes— Rails— Station Buildings— Loco- 
motives, Coaches and Cars. O^erafiTip'.— Introductory— Freight— Pas- 
sengers — Engine Drivers — Repairs to Track — Repairs of Machinery — 
Civil Engineer — Superintendent — Supplies of Material — Receipts — Dis- 
bursements — Statistics — Running Trains — Competition — Financie.i 
Management — General Remarks. 

JoliiisOFi. Tlie Coal Trade of British America ; 

With Researches on the Characters and Practical Values 
of American and Foreign Coals. By Walter R. Johnson, 
Civil and Mining Engineer and Chemist. 8vo $2.00 

This volume contains the results of the experiments made for the 
Navy Department, upon which their Coal contracts are now based. 

Johnston. Instriictioiis for ■ the Analysis of 
Soils, Limestones and Manures. 

By J. F. W. Johnston. 12mo 38 

Larkin. The Practical Brass and Iron Found- 
er's Guide; 

A Concise Treatise on the Art of Brass Founding, Mould- 
ing, etc. By James Larkin. 12mo., cloth $1.25 

Leslie's (Miss) Complete Cookery; 

Directions for Cookery in its Various Branches. By Miss 
Leslie. 58th thousand. Thoroughly revised ; with the 
addition of New Receipts, In one volume, 12mo., half 

bound, or in sheep $1.25 

13 



PEACTICAL AND SCIEWTIFIO BOOKS, 

Leslie's (Miss) Ladies' House Book; 

A Manual of Domestic Economy. 20tli revised edition. 
12mo., sheep , $1.25 

Leslie's (Miss) Two Himdred Receipts in 
Freiicli Cookeiy. 

Clotli, 12mo 25 

Lieber. Assayer's Guide; 

Or, Practical Directions to Assayers, Miners and Smelters, 
for the Tests and Assays, by Heat and by Wet Processes, 
of the Ores of all the principal Metals, and of Gold and 
Silver Coins and Alloys. By Oscar M. Lieber, late^^eolo- 
gist to the State of Mississippi. 12mo. With illustra- 
tions $1.25 

" Among the indispensable works for this purpose, is this little 
guide.''— Artizan. 

Lowig. Principles of Organic and Pliysiologi' 
cal Chemistry. 

By Dr. Carl Lowig, Doctor of Medicine and Philosophy; 
Ordinary Professor of Chemistry in the University of 
Zurich ; Author of " Chemie des Organischen Verbindun 
gen." Translated by. Daniel Breed, M. D., of the U. S. 
Patent Office ; late of the Laboratory of Liebig and Lowig. 
8vo., sheep $3.50 

MarWe Worker's Mamial; 

Containing Practical Information respecting Marbles in 
general, their Cutting, Working and Polishing, Veneer- 
ing, etc., etc. 12mo., cloth , $1.25 

Miles. A Plain Treatise on Horse-shoeing. 

With Illustrations. By William Miles, Author of " The 
Horse's Foot." $1,00 

14 



PUBLISHED BY HENBY CABEY BAIED. 

Main & Brown. Tlie Marine Sleaai-Engme. 

By Thomas J. Main, F.R. Ast. S. Mathematical Professor 
at the Royal Naval College, Portsmouth, and Thomas 
Brown, Assoc. Inst. C. E. Chief Engineer R. N. attached 
to the Royal Naval College. Authors of "Questions Con- 
nected with the Marine Steam-Engine," and the " Indi- 
cator and Dynamometer. ' ' With. Numerous Illustrations. 

In one Volume, 8vo $5.00 

CONTENTS.— Introductory Chapter, The Boiler, The Engine, Get- 
ting up Steam, Duties to Machinery when under Steam, Duties to En- 
gine, &.C., on arriving in harbor, Miscellaneous, Appendix. 

Main & Brown. Questions on Subjects Con- 
nected with the Marine-Steam Engine, 

An(^ Examination Papers ; with Hints for their Solution. 
By Tliomas J. Main, Professor of Mathematics Royal Naval 
College, and Thomas Brown, Chief Engineer R. N. 12mo., 
clotli $1.50 

Main & Brown. The Indicator and Dynamo- 
meter, 

With their Practical Applications to the Steam Engine. 
By Thomas J. Main and Thomas Brown. With Illustra- 
tions. 8vo., cloth $1.50 



Morfit, A Treatise on Chemistry 

Applied to the Manufactuke of Soap and Candles ; "being 
a Thorough Exposition, in all their Minutiae, of the prin- 
ciples and Practice of the Trade, based upon the most 
recent Discoveries in Science and Art. By Campbell 
Morfit, Professor of Analytical and Applied Chemistry in 
the University of Maryland. A new and improved edi- 
tion. Illustrated with 260 Engravings on Wood. Com- 
plete in one volume, large 8vo $7.50 

CONTEHSTTS.— CHAPTER I. The History of the Art and its Rela- 
tions to Science— II. Chemical Combination— III. Alkalies and Alka- 
line Earths— IV, Alkalimentary— V. Acids— VI. Origin and Composi- 
tion of Fatty Matters— VII. Saponifiable Fats— Vegetable Fats— Ani- 
mal Fats— Waxes— VIII. Action of Heat and Mineral Acids of Fatty 
Matters— IX. Volatile or Essential Oils, and Resins— X. The Proxi- 
mate Principles of Fats — Their Composition and Properties — Basic 
Constituents of Fats— XI. Theory of Saponification- XII. Utensils 
Requisite for a Soap Factory — XIII. Preparatory INIanipulations in 
the Process of Making Soap — Preparation of the Lyes— XIV. Hard 

15 



PKACTICAI. AWD SCIETyTTIFIG BOOKS, 

Soaps— XV. Soft Soaps— XVI. Soaps by the Cold Process— XVII. Sili 
cated Soaps— XVIII. Toilet Soaps— XIX. Patent Soaps— XX. Fraud 
UQd Adulterations in the Manufacture of Soap — XXI. Candles — XXII. 
Illumination— XXIII. Philosophy of Flame— XXIV. Raw Material 
for Candles— Purification and Bleaching of Suet— XXV. Wicks — XXVI. 
Dipped Candles— XXVII. Moulded Candles— XXVIII. Stearin Candles 
— XXIX. Stearic Acid Candles — "Star" or "Adamantine" Candles— 
SaponifiGation by Lime— Saponification by Lime and Sulphurous Acid 
—Saponification by Sulphuric Acid— Saponification by the combined 
action of Heat, Pressure and Steam — XXX. Spermaceti Candles — 
XXXI. Wax Candles— XXXII. Composite Candles— XXXIII. Paraffin 
—XXXIV. Patent Candles— XXXV. Hydrometers and Thermometers, 

Mortimer. PjToteclmist's Companion; 

Or, a Familiar System of Fire-works. By Gr. W. Morti- 
mer. Illustrated bj numerous Engravings. 12mo$1.25 

Napier. Mamial of ElectrO'Metailurgy ; 

Including tlie Application of the Art to Manufacturing 
Processes. By James Napier. From the second London 
edition, revised and enlarged. Illustrated bj Engrav- 
ings. In one volume, 12mo $1.50 

' Napier's Electro-Metallurgy is generally regarded as the very best 
Practical Treatise on the Subject in the English Language. 

CO]SrTEN"TS.— History of the Art of Electro-Metallurgy— Descri])- 
tion of Galvanic Batteries, and their respective Peculiarities — Elec- 
trotype Processes — Miscellaneous Applications of the Process of Coat- 
ing ^^ath Copper — Bronzing — Decomposition of ' Metals upon one 
another— Electro-Plating— Electro-Gilding— Results of Experiments 
on the Deposition of other Metals as Coatings, Theoretical Observa- 
tions. 

Norris's Hand-book for Locomoliye Eogineers 
and Machinists; 

• Comprising the Calculations fot Constructing Locomo- 
tives, Manner of setting Valves, etc., etc. By Septimus 
Norris, Civil and Mechanical Engineer. In one volume 
12mo., with Illustrations $2.00 

" With pleasure do we meet with such a work as Messrs, Norris 
and Baird have given us." — Artizan. 

" In this work he has given us what are called 'the secrets of the 
business,' in the rules to construct locomotives, in order that the mil- 
lion should be learned in all things."— iVienZi^c American. 

N} Strom. A Treatise on Screw-Propellers aod 
tlieir Steam-Engines ; 

With Practical Rules and Examples by which to Calcu- 
late and Construct the same for any description of "Ves- 
sels. By J. W. Nystrom. Illustrated by over thirty 
jar:;e Working Drawings. In one volume, octavo. ..$6.00 



. PUBLISHED BY HENRY CAREY BAIRD. 

Overman. The Mamifactiire of Iron in all ils 
Varions Branches; 

To wliich is added an Essay on the Manufacture of Steel. 
By Frederick Overman, Mining Engineer. With one 
hundred and fifty Wood Engravings. Third edition. In 
one volume, octavo, five hundred pages $7.50 

" We have now to announce the appearance of another valuable 
^ ork on the subject, which, in our humble opinion, supplies any defi- 
ciencj^ which late improvements and discoveries may have caused, 
from the lapse of time since the date of ' Mushet' and ' Schrivenor.' 
it is the production of one of our Trans-Atlantic brethren, Mr. Fred- 
erick Overman, Mining Engineer ; and we do not hesitate to set it 
(iovvn as a work of great importance to all connected with the iron in- 
terests ; one Avhich, while it is sufficiently technological fully to ex- 
plain chemical analysis, and the various phenomena of iron under 
different circumstances, to the satisfaction of the most fastidious, is 
written in that clear and comprehensive style as to be available to the 
capacity of the humblest mind, and consequently will be of much ad- 
vantage to those works where the proprietors may see the desirability 
of placing it in the hands of their operatives.''— London Mining 
Journal. 

Painter, Gilder and Varnisher's Companion; 

Containing Rules and Regulations in every thing relating 
to the Arts of Painting, Grilding, Varnishing and Glass 
Staining ; with numerous useful and valuable Receipts ; 
Tests for the detection of Adulterations in Oils and 
Colors ; and a statement of the Diseases and Accidents to 
which Painters, Gilders and Varnishers are particularly 
liable, with the simplest methods of Prevention and 
Remedy. Eighth edition. To which are added Complete 
Instructions in Graining, Marbling, Sign Writing, and 
Gilding on Glass. 12mo., cloth.. $1.25 

Paper«Hanger's (The) Companion; 

In which the Practical Operations of the Trade are sys- 
tematically laid down ; with copious Directions Prepara- 
tory to Papering ; Preventions against the effect of Damp 
in Walls ; the various Cements and Pastes adapted to 
the several purposes of the Trade ; Observations and Di- 
rections for the Panelling and Ornamenting of Rooms, 
etc., etc. By James Arrowsmith. In one volume 
12mo $1.25 

Practical (The) Snrveyor's Guide; 

Containing the necessary information to make any per- 
son of common capacity a finished Land Surveyor, with- 

*17 



PBACTICAL AND SCIEIyTTIFIC BOOKS, 

out the aid of a Teacher. By Andrew Duncan, Land 
Surveyor and Civil Engineer. 12nio 81.25 

Having had an experience as a Practical Surveyor, etc., of thirty- 
years, it is believed that the author of this volume possesses a thorough 
knowledge of the wants of the profession ; and never having met with 
any work sufficiently concise and instructive in the several details 
necessary for the proper qualification of the Surveyor, it has been hia 
object to supply that want. Among other important matters in the 
book, will be found the following : 

Instructions in levelling and profiling, with a new and speedy plan 
of setting grades on rail and plank roads — the method of inflecting 
curves — the description and design of ?«*iew instrument, whereby dis- 
tances are found at once, without any calculation — a new method of 
surveying anj- tract of land by measuring one line through it — a geo- 
metrical method of correcting surveys taken with the cgmpass, to fit 
them for calculation— a short method of finding the angles from the 
courses, and vice versa— the method of surveying with the compass 
through any mine or iron works, and to correct the deflections of the 
needle by attraction — description of an instrument by the help of 
which any one may measure a map by inspection, without calculation 
— a new and short method of calculation, wherein fewer figures are 
used— the method of correcting the diurnal variation of the needle 
— various methods of plotting and embellishing maps — the most cor- 
rect method of laying off plots with the pole, etc.— description of a 
new compass contrived by the author, etc., etc. 

Railroati Engineer's Pocket Companion for tlie 
Field. 

By W. Griswold. 12mo., tucks $1.25 

Kegnaiilt. Elements of Chemistry. 

By M. V. Regnault. Translated from the French by T. 
Forrest Betton, M.D., and edited, with notes, by James 
C. Booth, Melter and Refiner U. S. Mint, and William L. 
Faber, Metallurgist and Mining Engineer. Illustrated by 
nearly 700 wood engravings. Comprising nearly 1,500 
pages. In two volumes, 8vo., cloth $10.00 

Rural Chemistry; 

An Elementary Introduction to the Study of the Science, 
in its relation to Agriculture and the Arts of Life. By 
Edward Solly, Professor of Chemistry in the Horticul- 
tural Society of London. From the third improved Lon- 
don edition. 12mo $1.50 

Shunk. A Practical Treatise 

On Railway Curves, and Location fok Young Engineers. 
ByWm. F. Shunk, Civil Engineer. Timo $1.0(! 

Strength and Other Properties of Metals; 

Reports of Experiments on the Strength and other Pro- 



PUBLISHED BY HENRY CAREY BAIRD. 

perties of Metals for Cannon. With a Description of the 
Machines for Testing Metals, and of the Classification of 
Cannon in service. By Officers of the Ordnance Depart- 
ment U. S. Army. By authority of the Secretary of 
¥'-niilng' and originar a^tacks,l)ased upon the peculiaV advantaff^s'ol 

The best Treatise on Cast-iron extant. 



TaMes Showing the Weight 



Of Rounp, Square and Flat Bar Iron, Steel, etc., hy 
Measurement. Cloth 50 

Taylor. Statistics of Coal; 

Including Mineral Bituminous Substances employed in 
Arts and Manufactures ; with their Geographical, Geo- 
logical and Commercial Distribution, and Amount of Pro- 
duction and Consumption on the American Continent. 
With Incidental Statistics of the Iron Manufacture. By 
R. C. Taylor. Second edition, revised by S. S. Halde- 
man. Illustrated by five Maps and many Wood Engrav- 
ings. 8vo., cloth $6.00 

Templeton. The Practical Examinator on 
Steam and the Steam Engine ; 

With Instructive References relative thereto, arranged 
for the use of Engineers, Students, and others. By Wm. 
Templeton, Engineer. 12mo...., $1.25 

This work was originally written for the author's private use. He 
wa^ prevailed upon by various Engineers, who had seen the notes, to 
cortsent to its publication, from their eager expression of belief that 
It would be equally useful to them as it had been to himself. 

Til and Sheet Iron Worker's Instructor; 

Comprising complete Descriptions of the necessary Pat- 
terns and Machinery, and the Processes of Calculating 
Dimensions, Cutting, Joining, Raising, Soldering, etc. 
etc. With numerous Illustrations. , ....$2.50 

Treatise (A) on a Box of Instrnments, 

And the Slide Rule ; with the Theory of Trigonometry 
and Logarithms, including Practical Geometry, Survey 
ing, Measuring of Timber, Cask and Malt Gauging 

19 



PKACTICAL AND SCrEJSTTIFIO BOOKS, 

Heiglits and Distances. By Thomas Kentishl In one 
volume, 12mo $1.25 

A volume of inestimable value to Engineers, Gaugers, Students, and 
t)thers. 

years, it is believed that the author of this volume possesses a tho. vmgi 
knowledge of the wants of the profession ; and never having met witl 
onxr ^vnrk Piifficientlv conci'e and ixis+T-n^^-ix-p in +>-p spv-^'T-d (l':>ta^i 

With an Historical Account of its Rise, Progress, and 
Present Condition. Also, Practical Suggestions in regard 
to Insulation and Protection from the Effects of Light- 
ning. Together with an Appendix containing several 
important Telegraphic Devices and Laws. Bj Lawrence 
Turnhull, M. D., Lecturer on Technical Chemistry at the 
Franklin Institute. Second edition. Revised and im- 
proved. Illustrated by numerous Engravings. 8vo..$2.50 

Turner's (The) Compaiiion; 

Containing Instruction in Concentric, Elliptic and Eccen- 
tric Turning ; also various Steel Plates of Chucks, Tools 
and Instruments ; and Directions for Using the Eccentric 
Cutter, Drill, Vertical Cutter and Rest ; with Patterns 
and Instructions for working them. 12mo., cloth.. $1.25 

Weatherley (Henry). Treatise on the Art of 
Boiling Sogar, Crystallizing, Lozenge 
making, Comfits, Gum Goods, 

12ino $2.0t 

Williams. On Heat and Steam; 

Embracing New Views of Vaporization, Condensation, 
and Expansion. By Charles Wye Williams. Illustrated. 
8vo S3.50 



SOCIAL SCIENCE. 

THE WORKS OF HENRY C. CAREY. 



"I challenge the production froin among the writers on political, 
economy of a more learned, philosophical, and convincing speculator' 
on that theme, than my distinguished fellow-citizen, Henry C. Carey. 
The works he has published in support of the protective policy, are 
remarkable for profound research, extensive range of inquiry, rare 
logical acumen, and a consummate knowledge of hisiovy.'"— Speech of 
Hon. Edward Joy Morris^ in the House of Rejivesentatives of the UniUd 
States^ February 2, 1859. 
- 20 



PUBLISHED BY HEJ^BY CAREY BAIRD. 



THE WORKS OF HENRY C. CAREY. 

" Henry C. Carey, the best known and ablest economist of North 
America. ***** iq Europe he is principally known by his 
striking and original attacks, based upon the peculiar advantages of 
American experience, on some of the principal doctrines, especially 
Malthus' ' Theory of Population' and Ricardo's teachings. His views 
have been largely adopted and thoroughly discussed in Europe."— 
" The German Political Lexicon,^' Edited by Bluntschli and Brater. Leipsic, , 
1858. 

" We believe that your labors mark an era in the science of political 
economy. To your researches and lucid arguments are we indebted 
for the explosion of the absurdities of Malthus, Say, and Ricardo, in 
regard to the inability of the earth to meet the demands of a growing 
population. American industry owes you a debt which cannot be re- 
paid, and which it will ever be proud to acknowledge. — From a Letter 
of Hon. George W. Scranton, M. C, Hon. William Jessup, and over sixty 
influential citizens of Luzerne County, Pennsylvania, to Henry C. Carey, 
April 3, 1859. 

Finandal Crises; 

Their Causes and EflFects. 8vo., paper 25 

French and Amerkan Tariffs, 

Compared in a Series of Letters addressed to Mons. M. 
Chevalier. 8vo., paper.... 25 

Hariiiony (Tlie) of Interests ; 

Agricultural,. Manufacturing and Commercial. *8vo., 

paper 75 

Cloth $1.50 

" We can safely recommend this remarkable work to all who wish 
to investigate the causes of the progress or decline of industrial com- 
munities."— 5ZacA;wood's Magazine. 

Letters to tlie President of the United States. 

Svo.j Paper 50 



Miscellaneous Works; 



Comprising ''Harmony of Interests," "Money," "Let- 
ters to the President," "French and American Tariffs," 
and " Financial Crises." One volume, Svo $3.00 

Money; A Lecture 

Before the New York Geographical and Statistical So- 
ciety. Svo., paper 25 

21 





PSACTICAI. AND SCIENTIFIC BOOKS, 




THi 


: WORKS OF HENRY C. CAREY. 


Past 

8vo 


(The), 


the Present, 


and the Future. 

$2.50 


12mo 




$1.50 



" Full of important facts bearing on topics that are now agitating 
&11 Europe. * * * These quotations will only whet the appetite 
of the scientific reader to devour the whole work. It is a book full of 
valuable information."— Economist 

" Decidedly a book to be read by all who take an interest in the pro- 
gress of social science."— Spectoior. 

"A Southern man myself, never given to tariff doctrines, I confess to 
have been convinced by his reasoning, and, thank Heaven, have not 
now to learn the difference between dogged obstinacy and consistency. 
' Ye gods, give us but light !' should be the motto of every inquirer 
after truth, but for far different and better purposes than that which, 
prompted the exclamation.'' — The late John S. Skinner. 

" A volume of extensive information, deep thought, high intelli- 
gence, and moreover of material utility." — London Morning Advertiser. 

" Emanating from an active intellect, remarkable for distinct views 
and sincere convictions."— £rito7inia. 

" ' The Past, Present, and Future,' is a vast summary of progressive 
philosophy, wherein he demonstrates the benefit of political economy 
in the onward progress of mankind, which, ruled and directed by over- 
whelming influences of an exterior nature, advances little by little, 
until these exterior influences are rendered subservient in their turn, 
to increase as much as possible the extent of their wealth and riches." 
— Dictionnaire Universel des Contemporains. Par G, Vapereau. Paris, 
1858. 

Principles of Social Science. 

Three volumes, 8vo., clotli ^10.00 

COIvrTENTS.— Volume I. Of Science and its Methods— Of Man, 
the Subject of Social Science — Of Increase in the Numbers of Mankind 
—Of the Occupation of the Earth— Of Value— Of Wealth— Of the For- 
mation of Society— Of Appropriation— Of Changes of Matter in Place 
— Of M hanical and Chemical Changes in the Forms of Matter. Vol- 
ume II. Of Vital Changes in the Form of Matter— Of the Instrument 
of Assoc.ation. Volume III. Of Production and Consumption — Of 
Accumulation— Of Circulation— Of Distribution— Of Concentration 
and Centralization— Of Competition— Of Population— Of Food and 
Population— Of Colonization — Of the Blalthusian Theory — Of Com- 
merce— Of the Societary Organization— Of Social Science. 

" I have no desire here to reproach Mr. Malthus with the extreme 
lightness of his scientific baggage. In his day, biology, animal and 
vegetable chemistry, the relations of the various portions of the hu- 
man organism, etc. etc., had made but little progress, and it is to the 
general ignorance in reference to these questions that we must, as I 
think, look for explanation of the fact that he should, with so much 
confldence, in reference to so very grave a subject, have ventured to 
suggest a formula so arbitrary in its character, and one whose hollow- 
ness becomes now so clearly manifest. Mr. Carey's advantage over 
him, both as to facts and logic, is certainly due in great part to the 
progress that has since been made in all the sciences connected with 
life ; but then, how admirably has he profited of them ! How entirely 
is he au courant of all these branches of knowledge which, whether 



PUBLISHED BY HENBY CABERS BAIBD. 
THE WORKS OF HENRY C. CAREY. 

directly or indirectly, bear upon his subject ! With what skill does he 
ask of each and every of them all that it can be made to furnish, 
whether of facts or arguments ! With what elevated views, ana 
v/hat amplitude of means, does he go forward in his work ! Abov« 
all, how thorough in his scientific caution ! Accumulating inductions, 
and presenting for consideration facts the most undoubted and proba 
bilities of the highest kind, he yet affirms nothing, contenting himself 
with showing that his •opponent had no good reason for affirming the 
nature of the progression, nor the time of duplication, nor the gene- 
ralization which takes the facts of an individual case and deduces 
from them a law for every race, every climate, every civilization, 
every condition, moral or physical, permanent and transient, 
healthy or unhealthy, of the various populations of the many coun- 
tries of the world. Then, having reduced the theory to the level of a 
mere hypothesis, he crushes it to atoms under the weight of facts." — 
M. Be Fontenay in the ^^Journal des Economistes.'^ Paris, September, 1862. 

" This book is so abundantly full of notices, facts, comparisons, cal- 
culations, and arguments, that too much would be lost 'by laying a 
part of it before the eye of the reader. The work is vast and severe 
in its conception and aim, and is far removed from the common run 
of the books on similar subjects." — II Mondo Letterario, Turin. 

'''in political economy, America is represented by one of the 
strongest and most original writers of the age, Henry C. Carey, of 
Philadelphia. *x-********* 

" His theory of Rents is regarded as a complete demonstration tha't 
the popular views derived from Ricardo are erroneous ; and on the 
subject of Protection, he is generally confessed to be the master- 
thinker of his country." — Westminster Review. 

" Both in America and on the Continent, Mr. Henry Carey has ac- 
quired a great name as a political economist. ***** 

" His refutation of Malthus and Ricardo we consider most triumph- 
ant. "^LondoJi Critic. 

" Mr. Carey began his publication of Principles twenty years ago ; 
he is certainly a mature and deliberate writer. More than this, he is 
readable : his pages swarm with illustrative facts and with American 
instances. ************ 

" We are in great charity with books which, like Mr. Carey's, theo- 
rize with excessive boldness, when the author, as does Mr. Carey, 
possesses information and reasoning power."— London Athenccum. 

" Those who would fight against the insatiate greed and unscrupu- 
lous misrepresentations of the Manchester school, which we have fre-i 
quently exposed, without any of their organs having ever dared to 
make reply, will find in this and Mr. Carey's other works an immense 
store of arms and ammunition. ******** 

•' An author who has, among the political economists of Germany 
and France, numerous readers, is worth attentive perusal in Eng- 
land."— iondon Statesman. 

" Of all the varied answers to the old cry of human nature, ' Who 
will show us any good V none are more sententious than Mr. Carey's. 
He says to Kings, Presidents, and People, ' Keep the nation at work, 
and the greater the variety of employments the better.' He is seek- 
ing and elucidating the great radical lawe of matter as regards man. 
He is at once the apostle and evangelist of temporal righteousness." 
— National Intelligencer. 

" A work which we believe to be the greatest ever written by an 
American, and one which will in future ages be pointed out as the 
most successful effort of its time to form the great scientia scicntiarum.'* 
—Philadelphia Evening Bulletin. 

23 



ir'HACTICAL AND SCIENTIFIC BOOKS, 
THE WORKS OF HENRY C. CAREY. 

Tlie Slave Trade, Domestic and Foreign; 

Why it Exists, and How it may be ExtinguisTied. 12mo., 
cloth $1.50 

CONTENTS.— The Wide Extent of Slavery— Of Slavery in the 
British Colonies— Of Slavery in the United States— Of Emancipation 
in the British Colonies — How Man passes from Poverty and Slavery 
toward Wealth and Freedom — How Wealth tends to Increase — Hoav 
Labor acquires Value and Man becomes Free — How Man passes from 
Wealth and Freedom toward Poverty and Slavery — How Slavery 
grew, and How it is now maintained in the West Indies — How Slavery 
grew, and is maintained in the United States — How Slavery grows in 
Portugal and Turkey— How Slavery grows in India— How Slavery 
grows in Ireland and Scotland — How Slavery grows in England — 
How can Slavery be extinguished] — How Freedom grows in Northern 
Germany— How Freedom grows in Russia— How Freedom grows in 
Denmark— How Freedom grows in Spain and Belgium— Of the Duty 
of the People of the United States— Of the Duty of the People of Eng- 
land. 

" As a philosophical writer, Mr. Carey is remarkable for the union 
of comprehensive generalizations Avith a copious induction of facts. 
His research of principles never leads him to the neglect of details ; 
nor is his accumulation of instances ever at the expense of universal 
truth. He is, doubtless, intent on the investigation of laws, as the 
appropriate aim of science, but no passion for theory seduces him 
Into the region of pure speculation. His mind is no less historical 
than philosophical, and had he not chosen the severer branch in 
which his studies have borne such excellent fruit, he would have 
attained an eminent rank among the historians from whom the litera- 
ture of our country has received such signal illustration."— iS^ew York 
Tribune. 



French Poliiico-Econoniic Controversy, 

Between the Supporters of the Doctrines of Carey and 
of those of RiCAKDO and Malthus. By MM. De Fontenay, 
Dupuit, Baudrillart, and others. Translated from the 
"Journal desEconomistes," 1862-63. (Inpress.) 

Protection of Home Laboi' and Home Produc- 
tions 

Necessary to the Prosperity of the American Farmer. 
By H. C. Baird. Paper i3 

Smith. A Manual of Political Economy. 

By E. Peshine Smith. 12mo., cloth $1.2^ 

24 



